[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/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 62605dc5a..c89e4f6 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1645,9 +1645,10 @@
 		struct sockaddr_ax25 *sax = (struct sockaddr_ax25 *)msg->msg_name;
 		ax25_digi digi;
 		ax25_address src;
+		const unsigned char *mac = skb_mac_header(skb);
 
-		ax25_addr_parse(skb->mac.raw+1, skb->data-skb->mac.raw-1, &src, NULL, &digi, NULL, NULL);
-
+		ax25_addr_parse(mac + 1, skb->data - mac - 1, &src, NULL,
+				&digi, NULL, NULL);
 		sax->sax25_family = AF_AX25;
 		/* We set this correctly, even though we may not let the
 		   application know the digi calls further down (because it