drm/amdgpu: Fill xcp mem node in aquavanjaram

Implement callbacks to fill memory node information in aquavanjaram.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Le Ma <le.ma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>