drm/exynos: mixer: set the framebuffer source size by 0 when a layer is disabled

drm/exynos: mixer: set the framebuffer source size by 0 when a layer is disabled

Repeately turning on and off a layer, sometimes page fault occurs. This
problem seems to happen, because of H/W malfunction during turning on
the layer. But it can be solved by setting the framebuffer source size
by 0.

Kernel dump:
[   24.646472] PAGE FAULT occurred at 0x23000000 by 14650000.sysmmu(Page table base: 0x6d924000)
[   24.653515] 	Lv1 entry: 0x6e3b1001
[   24.656945] ------------[ cut here ]------------
[   24.661485] kernel BUG at drivers/iommu/exynos-iommu.c:358!
[   24.667030] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
[   24.672836] Modules linked in:
[   24.675872] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.0.0-00007-g838e0df #136
[   24.683145] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[   24.689214] task: c0e1aff0 ti: c0e0c000 task.ti: c0e0c000
[   24.694597] PC is at exynos_sysmmu_irq+0x1b8/0x2c4
[   24.699358] LR is at vprintk_emit+0x2a0/0x550
[   24.703684] pc : [<c036e530>]    lr : [<c00705d0>]    psr: 60070193
[   24.703684] sp : c0e0dd90  ip : 00000000  fp : c0e0ddcc
[   24.715121] r10: ee22e610  r9 : 00000000  r8 : ee22e628
[   24.720321] r7 : ed875810  r6 : 23000000  r5 : ed924000  r4 : 00000000
[   24.726820] r3 : c0e98098  r2 : 00000000  r1 : 00000000  r0 : ed6819c0
[   24.733321] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[   24.740685] Control: 10c5387d  Table: 6cb8c06a  DAC: 00000015
[   24.746403] Process swapper/0 (pid: 0, stack limit = 0xc0e0c210)
[   24.752383] Stack: (0xc0e0dd90 to 0xc0e0e000)
[   24.756718] dd80:                                     c0e0dd9c c0932868 ffff28da 6d924000
[   24.764864] dda0: ffff2990 ee22d8c0 ee22f060 00000049 c0e34e34 c0e0c000 00000000 00000000
[   24.773009] ddc0: c0e0de14 c0e0ddd0 c0071fd8 c036e384 ffffffff 7fffffff c0e0ddf4 ee22f000
[   24.781155] dde0: c0e95dfc c0e95de8 c0e0de14 ee22f000 ee22f060 ee22d8c0 c0e34e34 ee004670
[   24.789300] de00: ee010800 c0e0df00 c0e0de34 c0e0de18 c007221c c0071f80 ee22f000 ee22f060
[   24.797446] de20: 00000017 c0e34e34 c0e0de4c c0e0de38 c007520c c00721dc 00000049 ee0283c0
[   24.805591] de40: c0e0de64 c0e0de50 c0071540 c0075144 0000001c ee0283c0 c0e0de8c c0e0de68
[   24.813737] de60: c02fe7e8 c0071510 00000017 00000000 00000017 00000000 00000001 ee010800
[   24.821882] de80: c0e0dea4 c0e0de90 c0071540 c02fe750 c0e08a1c 00000000 c0e0ded4 c0e0dea8
[   24.830028] dea0: c0071880 c0071510 c0e0df00 f000200c 00000017 c0e140a8 c0e0df00 f0002000
[   24.838173] dec0: c0e96374 c0936d0c c0e0defc c0e0ded8 c0008734 c0071800 c0010d88 60070013
[   24.846319] dee0: ffffffff c0e0df34 00000001 c0e96374 c0e0df54 c0e0df00 c0014780 c0008700
[   24.854464] df00: 00000001 00000000 00000000 c0020720 c0e0c000 c0e13530 00000000 00000000
[   24.862610] df20: 00000001 c0e96374 c0936d0c c0e0df54 c0e0df58 c0e0df48 c0010d84 c0010d88
[   24.870755] df40: 60070013 ffffffff c0e0df94 c0e0df58 c00626d8 c0010d4c 00000001 c0eb1f00
[   24.878901] df60: c0e95ab0 c0e0df70 c0e1353c c0e0a580 00000002 c0e13e84 c0e09b88 c0e0df58
[   24.887046] df80: c092e1b8 ffffffff c0e0dfac c0e0df98 c0928880 c00622fc c0e13e10 c0eb1f00
[   24.895192] dfa0: c0e0dff4 c0e0dfb0 c0d57d2c c09287f8 ffffffff ffffffff c0d576ec 00000000
[   24.903337] dfc0: 00000000 c0dc1420 00000000 c0eb22d4 c0e134c0 c0dc141c c0e1c20c 4000406a
[   24.911483] dfe0: 410fc073 00000000 00000000 c0e0dff8 40008074 c0d57968 00000000 00000000
[   24.919641] [<c036e530>] (exynos_sysmmu_irq) from [<c0071fd8>] (handle_irq_event_percpu+0x64/0x25c)
[   24.928644] [<c0071fd8>] (handle_irq_event_percpu) from [<c007221c>] (handle_irq_event+0x4c/0x6c)
[   24.937483] [<c007221c>] (handle_irq_event) from [<c007520c>] (handle_level_irq+0xd4/0x14c)
[   24.945802] [<c007520c>] (handle_level_irq) from [<c0071540>] (generic_handle_irq+0x3c/0x4c)
[   24.954209] [<c0071540>] (generic_handle_irq) from [<c02fe7e8>] (combiner_handle_cascade_irq+0xa4/0x110)
[   24.963653] [<c02fe7e8>] (combiner_handle_cascade_irq) from [<c0071540>] (generic_handle_irq+0x3c/0x4c)
[   24.973009] [<c0071540>] (generic_handle_irq) from [<c0071880>] (__handle_domain_irq+0x8c/0xfc)
[   24.981676] [<c0071880>] (__handle_domain_irq) from [<c0008734>] (gic_handle_irq+0x40/0x78)
[   24.989994] [<c0008734>] (gic_handle_irq) from [<c0014780>] (__irq_svc+0x40/0x74)
[   24.997440] Exception stack(0xc0e0df00 to 0xc0e0df48)
[   25.002469] df00: 00000001 00000000 00000000 c0020720 c0e0c000 c0e13530 00000000 00000000
[   25.010616] df20: 00000001 c0e96374 c0936d0c c0e0df54 c0e0df58 c0e0df48 c0010d84 c0010d88
[   25.018757] df40: 60070013 ffffffff
[   25.022234] [<c0014780>] (__irq_svc) from [<c0010d88>] (arch_cpu_idle+0x48/0x4c)
[   25.029595] [<c0010d88>] (arch_cpu_idle) from [<c00626d8>] (cpu_startup_entry+0x3e8/0x4bc)
[   25.037837] [<c00626d8>] (cpu_startup_entry) from [<c0928880>] (rest_init+0x94/0x98)
[   25.045544] [<c0928880>] (rest_init) from [<c0d57d2c>] (start_kernel+0x3d0/0x3dc)
[   25.052992] Code: e34c30e9 e5932004 e3520000 ca000018 (e7f001f2)
[   25.059058] ---[ end trace 91806a51727d6586 ]---

Change-Id: Ic134f206721e33335962d7e941741331ec72672b
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Hyungwon Hwang <human.hwang@samsung.com>