drm/amdgpu: Add query_ras_error_status for mmhub v1_8

Add query_ras_error_status callback for mmhub
v1_8. It will be used to log mmhub error status.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>