[IPV4]: Make icmp_sk_init() static.

This patch makes the needlessly global icmp_sk_init() static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/icmp.c

@@ -1144,7 +1144,7 @@ static void __net_exit icmp_sk_exit(struct net *net)
 	net->ipv4.icmp_sk = NULL;
 }
 
-int __net_init icmp_sk_init(struct net *net)
+static int __net_init icmp_sk_init(struct net *net)
 {
 	int i, err;