ax25: Stop using magic neighbour cache operations.

Before the ax25 stack calls dev_queue_xmit it always calls
ax25_type_trans which sets skb->protocol to ETH_P_AX25.

Which means that by looking at the protocol type it is possible to
detect IP packets that have not been munged by the ax25 stack in
ndo_start_xmit and call a function to munge them.

Rename ax25_neigh_xmit to ax25_ip_xmit and tweak the return type and
value to be appropriate for an ndo_start_xmit function.

Update all of the ax25 devices to test the protocol type for ETH_P_IP
and return ax25_ip_xmit as the first thing they do.  This preserves
the existing semantics of IP packet processing, but the timing will be
a little different as the IP packets now pass through the qdisc layer
before reaching the ax25 ip packet processing.

Remove the now unnecessary ax25 neighbour table operations.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index c12ec2c..17058c4 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -529,6 +529,9 @@
 {
 	struct mkiss *ax = netdev_priv(dev);
 
+	if (skb->protocol == htons(ETH_P_IP))
+		return ax25_ip_xmit(skb);
+
 	if (!netif_running(dev))  {
 		printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name);
 		return NETDEV_TX_BUSY;
@@ -641,7 +644,6 @@
 	.ndo_stop            = ax_close,
 	.ndo_start_xmit	     = ax_xmit,
 	.ndo_set_mac_address = ax_set_mac_address,
-	.ndo_neigh_construct = ax25_neigh_construct,
 };
 
 static void ax_setup(struct net_device *dev)
@@ -651,7 +653,6 @@
 	dev->hard_header_len = 0;
 	dev->addr_len        = 0;
 	dev->type            = ARPHRD_AX25;
-	dev->neigh_priv_len  = sizeof(struct ax25_neigh_priv);
 	dev->tx_queue_len    = 10;
 	dev->header_ops      = &ax25_header_ops;
 	dev->netdev_ops	     = &ax_netdev_ops;