ipv6: Get rid of rt6i_nexthop macro.

It just makes it harder to see 1) what the code is doing
and 2) grep for all users of dst{->,.}neighbour

Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -656,7 +656,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
 	 * layer address of our nexhop router
 	 */
 
-	if (rt->rt6i_nexthop == NULL)
+	if (rt->dst.neighbour == NULL)
 		ifa->flags &= ~IFA_F_OPTIMISTIC;
 
 	ifa->idev = idev;