drm/amd/display: dcn20_resource_construct reduce scope of FPU enabled

drm/amd/display: dcn20_resource_construct reduce scope of FPU enabled

Limit when FPU is enabled to only functions that does FPU operations for
dcn20_resource_construct, which gets called during driver
initialization.

Enabling FPU operation disables preemption.  Sleeping functions(mutex
(un)lock, memory allocation using GFP_KERNEL, etc.) should not be called
when preemption is disabled.

Fixes the following case caught by enabling
CONFIG_DEBUG_ATOMIC_SLEEP in kernel config
[    1.338434] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:281
[    1.347395] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 197, name: systemd-udevd
[    1.356356] CPU: 7 PID: 197 Comm: systemd-udevd Not tainted 5.13.0+ #3
[    1.356358] Hardware name: System manufacturer System Product Name/PRIME X570-PRO, BIOS 3405 02/01/2021
[    1.356360] Call Trace:
[    1.356361]  dump_stack+0x6b/0x86
[    1.356366]  ___might_sleep.cold+0x87/0x98
[    1.356370]  __might_sleep+0x4b/0x80
[    1.356372]  mutex_lock+0x21/0x50
[    1.356376]  smu_get_uclk_dpm_states+0x3f/0x80 [amdgpu]
[    1.356538]  pp_nv_get_uclk_dpm_states+0x35/0x50 [amdgpu]
[    1.356711]  init_soc_bounding_box+0xf9/0x210 [amdgpu]
[    1.356892]  ? create_object+0x20d/0x340
[    1.356897]  ? dcn20_resource_construct+0x46f/0xd30 [amdgpu]
[    1.357077]  dcn20_resource_construct+0x4b1/0xd30 [amdgpu]
...

Tested on: 5700XT (NAVI10 0x1002:0x731F 0x1DA2:0xE410 0xC1)

Cc: Christian König <christian.koenig@amd.com>
Cc: Hersen Wu <hersenxs.wu@amd.com>
Cc: Anson Jacob <Anson.Jacob@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Signed-off-by: Anson Jacob <Anson.Jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>