remove function during multi-function hot-add In case user want to cancel the hot-add operation, should roll back, device_del the added function that still don`t work. Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>