ipv6: remove duplicate neigh_ifdown

When device is being set to down, neigh_ifdown was being called
twice. Once from addrconf notifier and once from ndisc notifier.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -2672,7 +2672,6 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 	/* Flush routes if device is being removed or it is not loopback */
 	if (how || !(dev->flags & IFF_LOOPBACK))
 		rt6_ifdown(net, dev);
-	neigh_ifdown(&nd_tbl, dev);
 
 	idev = __in6_dev_get(dev);
 	if (idev == NULL)