Reduce stack size pointed by clang:

amdgpu_dm/amdgpu_dm.c:8655:13: error: stack frame size (1048) exceeds limit (1024) in 'amdgpu_dm_atomic_commit_tail' [-Werror,-Wframe-larger-than]
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Alan Liu <haoping.liu@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>