trivial mod_timer fixes for af_wanpipe.c

@@ -634,11 +634,8 @@
 	skb_queue_tail(&sk->write_queue,skb);
 	atomic_inc(&wp->packet_sent);
 
-	if (!(test_and_set_bit(0, &wp->timer))){
-		del_timer(&wp->tx_timer);
-		wp->tx_timer.expires = jiffies + 1;
-		add_timer(&wp->tx_timer);
-	}	
+	if (!(test_and_set_bit(0, &wp->timer)))
+		mod_timer(&wp->tx_timer, jiffies + 1);
 	
 	return(len);