Register RLC_SPM_MC_CNTL is not blocked by L1 policy, VF can
directly access it through MMIO during SRIOV runtime.

v2: use SOC15 interface to access registers
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: ZhenGuo Yin <zhenguo.yin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>