[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/decnet/dn_route.c b/net/decnet/dn_route.c
index 32a7db3..bb73bf1 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -504,7 +504,7 @@
 		goto drop_it;
 
 	skb_pull(skb, 20);
-	skb->h.raw = skb->data;
+	skb_reset_transport_header(skb);
 
 	/* Destination info */
 	ptr += 2;
@@ -542,7 +542,7 @@
 		goto drop_it;
 
 	skb_pull(skb, 5);
-	skb->h.raw = skb->data;
+	skb_reset_transport_header(skb);
 
 	cb->dst = *(__le16 *)ptr;
 	ptr += 2;