drm/amd/display: fix kernel_fpu_begin/_end() warnings

drm/amd/display: fix kernel_fpu_begin/_end() warnings

kernel_fpu_begin/_end() are already called inside dcn20_resource_construct,
and calling kernel_fpu_begin/_end() recursively triggers WARN_ON() when
CONFIG_X86_DEBUG_FPU is enabled.

[  107.060434] WARNING: CPU: 6 PID: 1370 at arch/x86/kernel/fpu/core.c:90 kernel_fpu_begin+0xbd/0xe0
<snip>
[  107.268197] Call Trace:
[  107.270751]  dcn20_patch_bounding_box+0x17/0x100 [amdgpu]
[  107.276204]  init_soc_bounding_box+0x1b3/0x5f0 [amdgpu]
[  107.281536]  ? _cond_resched+0x19/0x30
[  107.285307]  dcn20_resource_construct+0x3a9/0xa90 [amdgpu]
[  107.290957]  ? dcn20_resource_construct+0x3a9/0xa90 [amdgpu]
[  107.296621]  ? __alloc_pages_nodemask+0x16a/0x330
[  107.301476]  ? _cond_resched+0x19/0x30
[  107.305284]  ? kmem_cache_alloc_trace+0x197/0x230
[  107.310063]  ? _cond_resched+0x19/0x30
[  107.313783]  ? kmem_cache_alloc_trace+0x197/0x230
[  107.318691]  dcn20_create_resource_pool+0x42/0x70 [amdgpu]
[  107.324315]  dc_create_resource_pool+0x12d/0x170 [amdgpu]
[  107.329851]  dc_create+0x1b8/0x6a0 [amdgpu]
[  107.334013]  ? kmem_cache_alloc_trace+0x1e2/0x230
[  107.338832]  amdgpu_dm_init+0x13e/0x1c0 [amdgpu]
<snip>

Signed-off-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>