[NEIGH]: Make /proc/net/arp opening consistent with seq_net_open semantics

seq_open_net requires that first field of the seq->private data to be
struct seq_net_private. In reality this is a single pointer to a
struct net for now. The patch makes code consistent.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index a9dda29..09f9fc6 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -223,7 +223,7 @@
 extern void pneigh_for_each(struct neigh_table *tbl, void (*cb)(struct pneigh_entry *));
 
 struct neigh_seq_state {
-	struct net *net;
+	struct seq_net_private p;
 	struct neigh_table *tbl;
 	void *(*neigh_sub_iter)(struct neigh_seq_state *state,
 				struct neighbour *n, loff_t *pos);