Revert "net: Remove unused neighbour layer ops."

This reverts commit 5c3ddec73d.

S390 qeth driver actually still uses the setup ops.

Reported-by: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/neighbour.h

@@ -43,6 +43,7 @@ struct neigh_parms {
 #endif
 	struct net_device *dev;
 	struct neigh_parms *next;
+	int	(*neigh_setup)(struct neighbour *);
 	void	(*neigh_cleanup)(struct neighbour *);
 	struct neigh_table *tbl;