ath9k: Remove is_bslot_active

In the tx_last_beacon() callback, mac80211's beaconing
status can be used instead. The beacon tasklet doesn't require
it because it is disabled when removing a slot.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 4cce997..f74640c 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -363,7 +363,7 @@
 
 struct ath_vif {
 	int av_bslot;
-	bool is_bslot_active, primary_sta_vif;
+	bool primary_sta_vif;
 	__le64 tsf_adjust; /* TSF adjustment for staggered beacons */
 	struct ath_buf *av_bcbuf;
 };