netfilter: x_tables: use NFPROTO_* in extensions

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/xt_length.c b/net/netfilter/xt_length.c
index b8640f9..b8612d1 100644
--- a/net/netfilter/xt_length.c
+++ b/net/netfilter/xt_length.c
@@ -48,14 +48,14 @@
 static struct xt_match length_mt_reg[] __read_mostly = {
 	{
 		.name		= "length",
-		.family		= AF_INET,
+		.family		= NFPROTO_IPV4,
 		.match		= length_mt,
 		.matchsize	= sizeof(struct xt_length_info),
 		.me		= THIS_MODULE,
 	},
 	{
 		.name		= "length",
-		.family		= AF_INET6,
+		.family		= NFPROTO_IPV6,
 		.match		= length_mt6,
 		.matchsize	= sizeof(struct xt_length_info),
 		.me		= THIS_MODULE,