ntb_hw_amd: Update amd_ntb_get_link_status to support latest generation secondary topology
In the NTB secondary topology configuration of the latest generation,
the device behaves like an endpoint. Hence, add endpoint support and
update amd_ntb_get_link_status to accommodate endpoint devices.
Co-developed-by: Sanath S <Sanath.S@amd.com> Signed-off-by: Sanath S <Sanath.S@amd.com> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Jon Mason <jdmason@kudzu.us>