ath9k: remove unused bc_tstamp

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -417,7 +417,6 @@ struct ath_beacon {
 
 	u32 beaconq;
 	u32 bmisscnt;
-	u32 bc_tstamp;
 	struct ieee80211_vif *bslot[ATH_BCBUF];
 	int slottime;
 	int slotupdate;