drm/amdgpu: stop waiting on UVD messages before mapping them

amdgpu_bo_kmap() now always waits for moves to finish.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>