drm/amdgpu: switch UVD code to use UVD_NO_OP for padding
Replace packet2's with packet0 writes to UVD_NO_OP. The
value written to UVD_NO_OP does not matter.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>