drm/amdgpu: Use PSP program IH_RB_CNTL registers under SRIOV

[Why]
With L1 Policy applied, IH_RB_CNTL/RING cannot be accessed by VF.

[How]
Use PSP program IH_RB_CNTL in VF.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Yifan Zha <Yifan.Zha@amd.com>
Signed-off-by: Horace Chen <horace.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>