drm/amd/display: Remove redundant idle optimization check

drm/amd/display: Remove redundant idle optimization check

[Why]
Disable idle optimization for each atomic commit is unnecessary,
and can lead to a potential race condition.

[How]
Remove idle optimization check from amdgpu_dm_atomic_commit_tail()

Fixes: 196107eb1e15 ("drm/amd/display: Add IPS checks before dcn register access")
Cc: stable@vger.kernel.org
Reviewed-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>