[IPV6]: Remove bogus WARN_ON in Proxy-NA handling.

Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ndisc.c

@@ -967,8 +967,6 @@ static void ndisc_recv_na(struct sk_buff *skb)
 		    ipv6_devconf.forwarding && ipv6_devconf.proxy_ndp &&
 		    pneigh_lookup(&nd_tbl, &msg->target, dev, 0)) {
 			/* XXX: idev->cnf.prixy_ndp */
-			WARN_ON(skb->dst != NULL &&
-				((struct rt6_info *)skb->dst)->rt6i_idev);
 			goto out;
 		}