ath9k: fix beacon restart on channel change

Restart the beacon timers only if the beacon
was already configured. Otherwise beacons timers
are restarted unnecessarily in unassociated state too.

Cc: stable@kernel.org
Signed-off-by: NRajkumar Manoharan <rmanoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/main.c

@@ -285,6 +285,7 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
 	ath9k_hw_set_interrupts(ah, ah->imask);
 
 	if (!(sc->sc_flags & (SC_OP_OFFCHANNEL))) {
+		if (sc->sc_flags & SC_OP_BEACONS)
 			ath_beacon_config(sc, NULL);
 		ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work, 0);
 		ath_start_ani(common);