[NETFILTER]: constify nf_afinfo

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index 7bf5e4a..4011f8f 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -190,7 +190,7 @@
 	return ip_route_output_key((struct rtable **)dst, fl);
 }
 
-static struct nf_afinfo nf_ip_afinfo = {
+static const struct nf_afinfo nf_ip_afinfo = {
 	.family		= AF_INET,
 	.checksum	= nf_ip_checksum,
 	.route		= nf_ip_route,