tun: Turn tun_flow_init() into void fn

This routine doesn't fail since 9fdc6bef (tuntap: dont use a private kmem_cache)
so it makes sense to compact the code a little bit.
Signed-off-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -841,7 +841,7 @@ static const struct net_device_ops tap_netdev_ops = {
 #endif
 };
 
-static int tun_flow_init(struct tun_struct *tun)
+static void tun_flow_init(struct tun_struct *tun)
 {
 	int i;
 
@@ -852,8 +852,6 @@ static int tun_flow_init(struct tun_struct *tun)
 	setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun);
 	mod_timer(&tun->flow_gc_timer,
 		  round_jiffies_up(jiffies + tun->ageing_time));
-
-	return 0;
 }
 
 static void tun_flow_uninit(struct tun_struct *tun)
@@ -1662,10 +1660,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 			goto err_free_dev;
 
 		tun_net_init(dev);
-
-		err = tun_flow_init(tun);
-		if (err < 0)
-			goto err_free_dev;
+		tun_flow_init(tun);
 
 		dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
 			TUN_USER_FEATURES;