drm/amdgpu: Skip specific mmhub and sdma registers accessing under sriov

[Why]
SDMA0_CNTL and MMHUB system aperture related registers are blocked by L1 Policy.
Therefore, they cannot be accessed by VF and loged in violation.

[How]
For MMHUB registers, they will be programmed by PF. So VF will skip to program them in mmhubv3_0.
For SDMA0_CNTL which is a PF_only register, VF don't need to program it in sdma_v6_0.

Signed-off-by: Yifan Zha <Yifan.Zha@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>