ath9k: fix panic while cleaning up virtaul wifis

num_sec_wiphy means max secondary wifis that the driver can accomudate.
So cancelling wiphy work should be based on the presence of
secondary wifis.

Signed-off-by: Rajkumar Manoharan <rmanoharan@atheros.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 56d4a93..d45cf0b 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -1269,6 +1269,7 @@
 	struct ath_softc *sc = aphy->sc;
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_common *common = ath9k_hw_common(ah);
+	int i;
 
 	mutex_lock(&sc->mutex);
 
@@ -1281,7 +1282,12 @@
 	cancel_work_sync(&sc->paprd_work);
 	cancel_work_sync(&sc->hw_check_work);
 
-	if (!sc->num_sec_wiphy) {
+	for (i = 0; i < sc->num_sec_wiphy; i++) {
+		if (sc->sec_wiphy[i])
+			break;
+	}
+
+	if (i == sc->num_sec_wiphy) {
 		cancel_delayed_work_sync(&sc->wiphy_work);
 		cancel_work_sync(&sc->chan_work);
 	}