[NETNS]: Register neighbour table parameters in the correct namespace.

neigh_sysctl_register should register sysctl entries inside correct namespace
to avoid naming conflict. Typical example is a loopback. Entries for it
present in all namespaces.

Required to make inetdev_event working.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/neighbour.c

@@ -2741,7 +2741,8 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 	neigh_path[NEIGH_CTL_PATH_PROTO].procname = p_name;
 	neigh_path[NEIGH_CTL_PATH_PROTO].ctl_name = p_id;
 
-	t->sysctl_header = register_sysctl_paths(neigh_path, t->neigh_vars);
+	t->sysctl_header =
+		register_net_sysctl_table(p->net, neigh_path, t->neigh_vars);
 	if (!t->sysctl_header)
 		goto free_procname;