[SK_BUFF]: Introduce skb_network_header()

For the places where we need a pointer to the network header, it is still legal
to touch skb->nh.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/drivers/s390/net/qeth_main.c b/drivers/s390/net/qeth_main.c
index c0ee6d9..0ff29e0 100644
--- a/drivers/s390/net/qeth_main.c
+++ b/drivers/s390/net/qeth_main.c
@@ -3778,9 +3778,11 @@
 	}
 	/* try something else */
 	if (skb->protocol == ETH_P_IPV6)
-		return (skb->nh.raw[24] == 0xff) ? RTN_MULTICAST : 0;
+		return (skb_network_header(skb)[24] == 0xff) ?
+				RTN_MULTICAST : 0;
 	else if (skb->protocol == ETH_P_IP)
-		return ((skb->nh.raw[16] & 0xf0) == 0xe0) ? RTN_MULTICAST : 0;
+		return ((skb_network_header(skb)[16] & 0xf0) == 0xe0) ?
+				RTN_MULTICAST : 0;
 	/* ... */
 	if (!memcmp(skb->data, skb->dev->broadcast, 6))
 		return RTN_BROADCAST;