ath9k: enable control frame reception

Set control frame bit in rx filter if dynack processing has been activated
in order to enable ACK frame reception

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -400,7 +400,8 @@ u32 ath_calcrxfilter(struct ath_softc *sc)
 	if (sc->sc_ah->is_monitoring)
 		rfilt |= ATH9K_RX_FILTER_PROM;
 
-	if (sc->cur_chan->rxfilter & FIF_CONTROL)
+	if ((sc->cur_chan->rxfilter & FIF_CONTROL) ||
+	    sc->sc_ah->dynack.enabled)
 		rfilt |= ATH9K_RX_FILTER_CONTROL;
 
 	if ((sc->sc_ah->opmode == NL80211_IFTYPE_STATION) &&