[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/include/linux/if_vlan.h b/include/linux/if_vlan.h
index d103580..544490d 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -51,7 +51,7 @@
 
 static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
 {
-	return (struct vlan_ethhdr *)skb->mac.raw;
+	return (struct vlan_ethhdr *)skb_mac_header(skb);
 }
 
 struct vlan_hdr {