[SK_BUFF]: Introduce skb_reset_network_header(skb)

For the common, open coded 'skb->nh.raw = skb->data' operation, so that we can
later turn skb->nh.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 case, next 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/core/dev.c b/net/core/dev.c
index 560560f..1b07582 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1074,7 +1074,7 @@
 					printk(KERN_CRIT "protocol %04x is "
 					       "buggy, dev %s\n",
 					       skb2->protocol, dev->name);
-				skb2->nh.raw = skb2->data;
+				skb_reset_network_header(skb2);
 			}
 
 			skb2->h.raw = skb2->nh.raw;
@@ -1771,7 +1771,8 @@
 
 	__get_cpu_var(netdev_rx_stat).total++;
 
-	skb->h.raw = skb->nh.raw = skb->data;
+	skb_reset_network_header(skb);
+	skb->h.raw = skb->data;
 	skb->mac_len = skb->nh.raw - skb->mac.raw;
 
 	pt_prev = NULL;