[SK_BUFF]: Introduce ipv6_hdr(), remove skb->nh.ipv6h

Now the skb->nh union has just one member, .raw, i.e. it is just like the
skb->mac union, strange, no? I'm just leaving it like that till the transport
layer is done with, when we'll rename skb->mac.raw to skb->mac_header (or
->mac_header_offset?), ditto for ->{h,nh}.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
index 93c4223..538499a 100644
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -257,7 +257,7 @@
 
 static int xfrm6_tunnel_rcv(struct sk_buff *skb)
 {
-	struct ipv6hdr *iph = skb->nh.ipv6h;
+	struct ipv6hdr *iph = ipv6_hdr(skb);
 	__be32 spi;
 
 	spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&iph->saddr);