gtp: use icmp_ndo_send helper

Because gtp is calling icmp from network device context, it should use
the ndo helper so that the rate limiting applies correctly.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Harald Welte <laforge@gnumonks.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index af07ea7..672cd2c 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -546,8 +546,8 @@
 	    mtu < ntohs(iph->tot_len)) {
 		netdev_dbg(dev, "packet too big, fragmentation needed\n");
 		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
-		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
-			  htonl(mtu));
+		icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+			      htonl(mtu));
 		goto err_rt;
 	}