[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/ipv6/reassembly.c b/net/ipv6/reassembly.c
index ef29a7b..31d4271 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -726,7 +726,7 @@
 	}
 
 	hdr = ipv6_hdr(skb);
-	fhdr = (struct frag_hdr *)skb->h.raw;
+	fhdr = (struct frag_hdr *)skb_transport_header(skb);
 
 	if (!(fhdr->frag_off & htons(0xFFF9))) {
 		/* It is not a fragmented frame */