[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/net/ax25/ax25_out.c b/net/ax25/ax25_out.c
index 94557b1..5fc048d 100644
--- a/net/ax25/ax25_out.c
+++ b/net/ax25/ax25_out.c
@@ -351,8 +351,7 @@
 {
 	unsigned char *ptr;
 
-	skb->protocol = htons(ETH_P_AX25);
-	skb->dev      = ax25_fwd_dev(dev);
+	skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 
 	ptr  = skb_push(skb, 1);
 	*ptr = 0x00;			/* KISS */