Currently host-gpu io link is always reported as PCIe however, on some
A+A systems, there could be one xgmi link available. This change exposes
xgmi link via sysfs when it is present.
v2: fix includes (Alex)
Reviewed-by: Oak Zeng <oak.zeng@amd.com> Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com> Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>