ath9k: fix going to full-sleep on PS idle

The check for PS_WAIT_FOR_TX_ACK was inverted, the hardware should only go
to full sleep if no tx is pending.

Reported-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Cc: stable@vger.kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -118,13 +118,15 @@ void ath9k_ps_restore(struct ath_softc *sc)
 	if (--sc->ps_usecount != 0)
 		goto unlock;
 
-	if (sc->ps_idle && (sc->ps_flags & PS_WAIT_FOR_TX_ACK))
+	if (sc->ps_flags & PS_WAIT_FOR_TX_ACK)
+		goto unlock;
+
+	if (sc->ps_idle)
 		mode = ATH9K_PM_FULL_SLEEP;
 	else if (sc->ps_enabled &&
 		 !(sc->ps_flags & (PS_WAIT_FOR_BEACON |
 			      PS_WAIT_FOR_CAB |
-			      PS_WAIT_FOR_PSPOLL_DATA |
-			      PS_WAIT_FOR_TX_ACK)))
+			      PS_WAIT_FOR_PSPOLL_DATA)))
 		mode = ATH9K_PM_NETWORK_SLEEP;
 	else
 		goto unlock;