net: ipv4: fix rcu lockdep splat due to wrong annotation

syzbot triggered following splat when strict netlink
validation is enabled:

net/ipv4/devinet.c:1766 suspicious rcu_dereference_check() usage!

This occurs because we hold RTNL mutex, but no rcu read lock.
The second call site holds both, so just switch to the _rtnl variant.

Reported-by: syzbot+bad6e32808a3a97b1515@syzkaller.appspotmail.com
Fixes: 2638eb8 ("net: ipv4: provide __rcu annotation for ifa_list")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/devinet.c

@@ -1763,7 +1763,7 @@ static int in_dev_dump_addr(struct in_device *in_dev, struct sk_buff *skb,
 	int ip_idx = 0;
 	int err;
 
-	in_dev_for_each_ifa_rcu(ifa, in_dev) {
+	in_dev_for_each_ifa_rtnl(ifa, in_dev) {
 		if (ip_idx < s_ip_idx) {
 			ip_idx++;
 			continue;