[SK_BUFF]: Introduce skb_reset_transport_header(skb)

For the common, open coded 'skb->h.raw = skb->data' operation, so that we can
later turn skb->h.raw into a offset, reducing the size of struct sk_buff in
64bit land while possibly keeping it as a pointer on 32bit.

This one touches just the most simple cases:

skb->h.raw = skb->data;
skb->h.raw = {skb_push|[__]skb_pull}()

The next ones will handle the slightly more "complex" cases.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c
index c5239fc..b2bbe55 100644
--- a/net/x25/x25_in.c
+++ b/net/x25/x25_in.c
@@ -53,7 +53,7 @@
 
 		skb_queue_tail(&x25->fragment_queue, skb);
 
-		skbn->h.raw = skbn->data;
+		skb_reset_transport_header(skbn);
 
 		skbo = skb_dequeue(&x25->fragment_queue);
 		memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);