[IPV6]: TUNNEL6: Don't try to add multicast route twice.

Since addrconf_add_dev() has already called addrconf_add_mroute()
to added route for multicast prefix, there's no point to call it
again in addrconf_ip6_tnl_config().

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

net/ipv6/addrconf.c

@@ -2143,7 +2143,6 @@ static void addrconf_ip6_tnl_config(struct net_device *dev)
 		return;
 	}
 	ip6_tnl_add_linklocal(idev);
-	addrconf_add_mroute(dev);
 }
 
 static int addrconf_notify(struct notifier_block *this, unsigned long event,