lwtunnel: use kfree_skb() instead of vanilla kfree()

kfree_skb() is correct here.

Fixes: ffce41962ef6 ('lwtunnel: support dst output redirect function')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/lwtunnel.c

@@ -205,7 +205,7 @@ int __lwtunnel_output(struct sock *sk, struct sk_buff *skb,
 	return ret;
 
 drop:
-	kfree(skb);
+	kfree_skb(skb);
 
 	return ret;
 }