[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/drivers/net/appletalk/cops.c b/drivers/net/appletalk/cops.c
index 28cb79c..da6ffa8 100644
--- a/drivers/net/appletalk/cops.c
+++ b/drivers/net/appletalk/cops.c
@@ -855,7 +855,7 @@
 
         skb_reset_mac_header(skb);    /* Point to entire packet. */
         skb_pull(skb,3);
-        skb->h.raw      = skb->data;    /* Point to data (Skip header). */
+        skb_reset_transport_header(skb);    /* Point to data (Skip header). */
 
         /* Update the counters. */
         lp->stats.rx_packets++;