ath9k: Add a routine to tear down channel contexts

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/main.c b/drivers/net/wireless/ath/ath9k/main.c
index ed281ac..e5c523a 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -822,7 +822,8 @@
 	struct ath_common *common = ath9k_hw_common(ah);
 	bool prev_idle;
 
-	cancel_work_sync(&sc->chanctx_work);
+	ath9k_deinit_channel_context(sc);
+
 	mutex_lock(&sc->mutex);
 
 	ath_cancel_work(sc);