drm/amdgpu: Skip uvd and vce ring test for SRIOV

Since rptr would not be accessed on later secure asics in sriov, remove
the ring test.

Signed-off-by: Frank Min <Frank.Min@amd.com>
Signed-off-by: Xiangliang.Yu <Xiangliang.Yu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>