ath9k: Implement dev_tx_frames_pending callback.

This function returns true if there is atleast one frame
in any one of the tx queues.
Signed-off-by: NVivek Natarajan <vnatarajan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -2201,6 +2201,21 @@ static void ath9k_flush(struct ieee80211_hw *hw, bool drop)
 	ath9k_ps_restore(sc);
 }
 
+static bool ath9k_tx_frames_pending(struct ieee80211_hw *hw)
+{
+	struct ath_softc *sc = hw->priv;
+	int i;
+
+	for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
+		if (!ATH_TXQ_SETUP(sc, i))
+			continue;
+
+		if (ath9k_has_pending_frames(sc, &sc->tx.txq[i]))
+			return true;
+	}
+	return false;
+}
+
 struct ieee80211_ops ath9k_ops = {
 	.tx 		    = ath9k_tx,
 	.start 		    = ath9k_start,
@@ -2223,4 +2238,5 @@ struct ieee80211_ops ath9k_ops = {
 	.rfkill_poll        = ath9k_rfkill_poll_state,
 	.set_coverage_class = ath9k_set_coverage_class,
 	.flush		    = ath9k_flush,
+	.tx_frames_pending  = ath9k_tx_frames_pending,
 };