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>
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 66c5fe8..42108f0 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -400,7 +400,8 @@
 	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) &&