[SK_BUFF]: Introduce skb_transport_header(skb)

For the places where we need a pointer to the transport header, it is
still legal to touch skb->h.raw directly if just adding to,
subtracting from or setting it to another layer header.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 75d4d69..5f28887 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1585,9 +1585,10 @@
 
 	skb_set_transport_header(skb, lv);
 
-	SOCK_DEBUG(sk, "base=%p pos=%p\n", skb->data, skb->h.raw);
+	SOCK_DEBUG(sk, "base=%p pos=%p\n",
+		   skb->data, skb_transport_header(skb));
 
-	*skb->h.raw = AX25_UI;
+	*skb_transport_header(skb) = AX25_UI;
 
 	/* Datagram frames go straight out of the door as UI */
 	ax25_queue_xmit(skb, ax25->ax25_dev->dev);