netfilter: nf_tables: use RCU-safe list insertion when replacing rules

The patch 5e94846 ("netfilter: nf_tables: add insert operation") did
not include RCU-safe list insertion when replacing rules.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -1796,7 +1796,7 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb,
 				goto err2;
 			}
 			nft_rule_disactivate_next(net, old_rule);
-			list_add_tail(&rule->list, &old_rule->list);
+			list_add_tail_rcu(&rule->list, &old_rule->list);
 		} else {
 			err = -ENOENT;
 			goto err2;