drm/amdgpu: remove ib test for the second VCE Ring

it seems the VCE ring 1 ib test not reliable, remove it for now.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Tested-and-Reviewed-by: Sonny Jiang <sonny.jiang@amd.com>