atheros: define a common priv struct

hw code should never use private driver data, but
sometimes we need a backpointer so just stuff it on
the common ath struct.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath.h

@@ -56,6 +56,7 @@ struct ath_bus_ops {
 
 struct ath_common {
 	void *ah;
+	void *priv;
 	struct ieee80211_hw *hw;
 	int debug_mask;