drm/amdgpu/cz: remove commented out call to enable vce pg

This code path is not currently enabled now that we properly
respect the vce pg flags, so uncomment the actual pg calls
so the code is as it should be we are eventually able to
enable vce pg.

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