ar71xx: add missing return statement in ethernet mtu change op

Signed-off-by: Felix Fietkau <[email protected]>

SVN-Revision: 37756

target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c

@@ -1049,6 +1049,7 @@ static int ag71xx_change_mtu(struct net_device *dev, int new_mtu)
 		return -EINVAL;
 
 	dev->mtu = new_mtu;
+	return 0;
 }
 
 static const struct net_device_ops ag71xx_netdev_ops = {