ax25: Refactor to use private neighbour operations.

AX25 already has it's own private arp cache operations to isolate
it's abuse of dev_rebuild_header to transmit packets.  Add a function
ax25_neigh_construct that will allow all of the ax25 devices to
force using these operations, so that the generic arp code does
not need to.

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-hams@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hamradio/scc.c

@@ -1550,6 +1550,7 @@ static const struct net_device_ops scc_netdev_ops = {
 	.ndo_set_mac_address = scc_net_set_mac_address,
 	.ndo_get_stats       = scc_net_get_stats,
 	.ndo_do_ioctl        = scc_net_ioctl,
+	.ndo_neigh_construct = ax25_neigh_construct,
 };
 
 /* ----> Initialize device <----- */
@@ -1567,6 +1568,7 @@ static void scc_net_setup(struct net_device *dev)
 	dev->flags      = 0;
 
 	dev->type = ARPHRD_AX25;
+	dev->neigh_priv_len = sizeof(struct ax25_neigh_priv);
 	dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
 	dev->mtu = AX25_DEF_PACLEN;
 	dev->addr_len = AX25_ADDR_LEN;