[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/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 156a37f..2594f0f 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -653,7 +653,7 @@
 	head->nh.raw += sizeof(struct frag_hdr);
 
 	skb_shinfo(head)->frag_list = head->next;
-	head->h.raw = head->data;
+	skb_reset_transport_header(head);
 	skb_push(head, head->data - skb_network_header(head));
 	atomic_sub(head->truesize, &ip6_frag_mem);