[SK_BUFF]: Introduce skb_reset_mac_header(skb)

For the common, open coded 'skb->mac.raw = skb->data' operation, so that we can
later turn skb->mac.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/ieee80211/ieee80211_rx.c b/net/ieee80211/ieee80211_rx.c
index d5f5c66..f39bf7c 100644
--- a/net/ieee80211/ieee80211_rx.c
+++ b/net/ieee80211/ieee80211_rx.c
@@ -42,7 +42,7 @@
 	u16 fc = le16_to_cpu(hdr->frame_ctl);
 
 	skb->dev = ieee->dev;
-	skb->mac.raw = skb->data;
+	skb_reset_mac_header(skb);
 	skb_pull(skb, ieee80211_get_hdrlen(fc));
 	skb->pkt_type = PACKET_OTHERHOST;
 	skb->protocol = __constant_htons(ETH_P_80211_RAW);
@@ -789,10 +789,11 @@
 
 	if (skb2 != NULL) {
 		/* send to wireless media */
-		skb2->protocol = __constant_htons(ETH_P_802_3);
-		skb2->mac.raw = skb2->nh.raw = skb2->data;
-		/* skb2->nh.raw = skb2->data + ETH_HLEN; */
 		skb2->dev = dev;
+		skb2->protocol = __constant_htons(ETH_P_802_3);
+		skb_reset_mac_header(skb2);
+		skb2->nh.raw = skb2->data;
+		/* skb2->nh.raw = skb2->data + ETH_HLEN; */
 		dev_queue_xmit(skb2);
 	}
 #endif