ipip,gre,vti,sit: implement ndo_get_iflink

Don't use dev->iflink anymore.

CC: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 2cd0828..4bb7252 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -389,7 +389,6 @@
 		hlen = tdev->hard_header_len + tdev->needed_headroom;
 		mtu = tdev->mtu;
 	}
-	dev->iflink = tunnel->parms.link;
 
 	dev->needed_headroom = t_hlen + hlen;
 	mtu -= (dev->hard_header_len + t_hlen);
@@ -980,6 +979,14 @@
 }
 EXPORT_SYMBOL(ip_tunnel_get_link_net);
 
+int ip_tunnel_get_iflink(const struct net_device *dev)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+
+	return tunnel->parms.link;
+}
+EXPORT_SYMBOL(ip_tunnel_get_iflink);
+
 int ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
 				  struct rtnl_link_ops *ops, char *devname)
 {