netfilter: conntrack: fix indentation issue

A statement in an if block is not indented correctly. Fix this.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_netlink.c

@@ -2675,7 +2675,7 @@ static int ctnetlink_exp_dump_mask(struct sk_buff *skb,
 	ret = ctnetlink_dump_tuples_ip(skb, &m);
 	if (ret >= 0) {
 		l4proto = nf_ct_l4proto_find(tuple->dst.protonum);
-	ret = ctnetlink_dump_tuples_proto(skb, &m, l4proto);
+		ret = ctnetlink_dump_tuples_proto(skb, &m, l4proto);
 	}
 	rcu_read_unlock();