pds_vdpa: add support for vdpa and vdpamgmt interfaces

This is the vDPA device support, where we advertise that we can
support the virtio queues and deal with the configuration work
through the pds_core's adminq.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Message-Id: <20230519215632.12343-10-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>