drm/amdgpu: Program ring for vce instance 1 at its register space

We need program ring buffer on instance 1 register space domain,
when only if instance 1 available, with two instances or instance 0,
and we need only program instance 0 regsiter space domain for ring.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>