staging: gdm72xx: use list_move_tail instead of list_del/list_add_tail

Using list_move_tail() instead of list_del() + list_add_tail().

spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm72xx/gdm_usb.c

@@ -178,8 +178,7 @@ static struct usb_rx *get_rx_struct(struct rx_cxt *rx)
 	}
 
 	r = list_entry(rx->free_list.next, struct usb_rx, list);
-	list_del(&r->list);
-	list_add_tail(&r->list, &rx->used_list);
+	list_move_tail(&r->list, &rx->used_list);
 
 	return r;
 }