net: dsa: Add a private structure pointer to dsa_port

This is supposed to share information between the driver and the tagger,
or used by the tagger to keep some state. Its use is optional.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -210,6 +210,12 @@ struct dsa_port {
 	struct work_struct	xmit_work;
 	struct sk_buff_head	xmit_queue;
 
+	/*
+	 * Give the switch driver somewhere to hang its per-port private data
+	 * structures (accessible from the tagger).
+	 */
+	void *priv;
+
 	/*
 	 * Original copy of the master netdev ethtool_ops
 	 */