ath9k: Do not use local_bh_disable in ampdu_action

This was added during the early conversion of ampdu_action
to a sleeping callback. There is no need to do this - instead,
use the normal mutex that is acquired for all callbacks.
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -1684,7 +1684,7 @@ static int ath9k_ampdu_action(struct ieee80211_hw *hw,
 	struct ath_softc *sc = hw->priv;
 	int ret = 0;
 
-	local_bh_disable();
+	mutex_lock(&sc->mutex);
 
 	switch (action) {
 	case IEEE80211_AMPDU_RX_START:
@@ -1715,7 +1715,7 @@ static int ath9k_ampdu_action(struct ieee80211_hw *hw,
 		ath_err(ath9k_hw_common(sc->sc_ah), "Unknown AMPDU action\n");
 	}
 
-	local_bh_enable();
+	mutex_unlock(&sc->mutex);
 
 	return ret;
 }