Initial pass at a structure to store xgmi info.  xgmi is a high
speed cross gpu interconnect.
Acked-by: NHuang Rui <ray.huang@amd.com>
Acked-by: NSlava Abramov <slava.abramov@amd.com>
Reviewed-by :Shaoyun liu <Shaoyun.liu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NShaoyun Liu <Shaoyun.Liu@amd.com>