drm/amd/amdgpu: Remove workaround for suspend/resume in uvd7

The workaround is not required anymor and would result in
hangs during suspend/resume cycles if the uvd block were busy.

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Acked-by: Leo Liu <leo.liu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>