[SK_BUFF]: Introduce skb_mac_header()

For the places where we need a pointer to the mac header, it is still legal to
touch skb->mac.raw directly if just adding to, subtracting from or setting it
to another layer header.

This one also converts some more cases to skb_reset_mac_header() that my
regex missed as it had no spaces before nor after '=', ugh.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/slip.c b/drivers/net/slip.c
index 2f4b1de..65bd20f 100644
--- a/drivers/net/slip.c
+++ b/drivers/net/slip.c
@@ -363,7 +363,7 @@
 	}
 	skb->dev = sl->dev;
 	memcpy(skb_put(skb,count), sl->rbuff, count);
-	skb->mac.raw=skb->data;
+	skb_reset_mac_header(skb);
 	skb->protocol=htons(ETH_P_IP);
 	netif_rx(skb);
 	sl->dev->last_rx = jiffies;