Add new call back function in vhost-vdpa, this function will
set the event fd to kernel. This function will be called
in the vhost_dev_start and vhost_dev_stop
Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20211104164827.21911-6-lulu@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>