drm/amdgpu: skip get/update xgmi topology info when no psp exists

We don't currently have psp support for arcturus so provide a alternative
mechanism in the meantime.

Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>