netfilter: Add the missed return value check of nft_register_chain_type

There are some codes of netfilter module which did not check the return
value of nft_register_chain_type. Add the checks now.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv6/netfilter/nf_tables_ipv6.c

@@ -100,7 +100,10 @@ static int __init nf_tables_ipv6_init(void)
 {
 	int ret;
 
-	nft_register_chain_type(&filter_ipv6);
+	ret = nft_register_chain_type(&filter_ipv6);
+	if (ret < 0)
+		return ret;
+
 	ret = register_pernet_subsys(&nf_tables_ipv6_net_ops);
 	if (ret < 0)
 		nft_unregister_chain_type(&filter_ipv6);