ath9k: Fix TX hang poll routine

This is a backport of upstream commit: 332c5566

When TX is hung, the chip is reset. Ensure that
the chip is awake by using the PS wrappers.
Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

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

@@ -2065,7 +2065,9 @@ static void ath_tx_complete_poll_work(struct work_struct *work)
 
 	if (needreset) {
 		DPRINTF(sc, ATH_DBG_RESET, "tx hung, resetting the chip\n");
+		ath9k_ps_wakeup(sc);
 		ath_reset(sc, false);
+		ath9k_ps_restore(sc);
 	}
 
 	ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work,