[AX25] Introduce ax25_type_trans

Replacing the open coded equivalents and making ax25 look more like
a linux network protocol, i.e. more similar to inet.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index d9ea080..6279051 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -332,12 +332,10 @@
 		return;
 	}
 
-	skb->dev      = ax->dev;
 	spin_lock_bh(&ax->buflock);
 	memcpy(skb_put(skb,count), ax->rbuff, count);
 	spin_unlock_bh(&ax->buflock);
-	skb->mac.raw  = skb->data;
-	skb->protocol = htons(ETH_P_AX25);
+	skb->protocol = ax25_type_trans(skb, ax->dev);
 	netif_rx(skb);
 	ax->dev->last_rx = jiffies;
 	ax->rx_packets++;