[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_tr.h b/include/linux/if_tr.h
index 2f94cf2..046e9d9 100644
--- a/include/linux/if_tr.h
+++ b/include/linux/if_tr.h
@@ -47,7 +47,7 @@
 
 static inline struct trh_hdr *tr_hdr(const struct sk_buff *skb)
 {
-	return (struct trh_hdr *)skb->mac.raw;
+	return (struct trh_hdr *)skb_mac_header(skb);
 }
 #ifdef CONFIG_SYSCTL
 extern struct ctl_table tr_table[];