drm/msm/a6xx: Allocate enough space for GMU registers

drm/msm/a6xx: Allocate enough space for GMU registers

In commit 142639a52a01 ("drm/msm/a6xx: fix crashstate capture for
A650") we changed a6xx_get_gmu_registers() to read 3 sets of
registers. Unfortunately, we didn't change the memory allocation for
the array. That leads to a KASAN warning (this was on the chromeos-5.4
kernel, which has the problematic commit backported to it):

  BUG: KASAN: slab-out-of-bounds in _a6xx_get_gmu_registers+0x144/0x430
  Write of size 8 at addr ffffff80c89432b0 by task A618-worker/209
  CPU: 5 PID: 209 Comm: A618-worker Tainted: G        W         5.4.156-lockdep #22
  Hardware name: Google Lazor Limozeen without Touchscreen (rev5 - rev8) (DT)
  Call trace:
   dump_backtrace+0x0/0x248
   show_stack+0x20/0x2c
   dump_stack+0x128/0x1ec
   print_address_description+0x88/0x4a0
   __kasan_report+0xfc/0x120
   kasan_report+0x10/0x18
   __asan_report_store8_noabort+0x1c/0x24
   _a6xx_get_gmu_registers+0x144/0x430
   a6xx_gpu_state_get+0x330/0x25d4
   msm_gpu_crashstate_capture+0xa0/0x84c
   recover_worker+0x328/0x838
   kthread_worker_fn+0x32c/0x574
   kthread+0x2dc/0x39c
   ret_from_fork+0x10/0x18

  Allocated by task 209:
   __kasan_kmalloc+0xfc/0x1c4
   kasan_kmalloc+0xc/0x14
   kmem_cache_alloc_trace+0x1f0/0x2a0
   a6xx_gpu_state_get+0x164/0x25d4
   msm_gpu_crashstate_capture+0xa0/0x84c
   recover_worker+0x328/0x838
   kthread_worker_fn+0x32c/0x574
   kthread+0x2dc/0x39c
   ret_from_fork+0x10/0x18

Fixes: 142639a52a01 ("drm/msm/a6xx: fix crashstate capture for A650")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20211103153049.1.Idfa574ccb529d17b69db3a1852e49b580132035c@changeid
Signed-off-by: Rob Clark <robdclark@chromium.org>