ath9k: Enable U-APSD AP mode support

mac80211 handles the actual operations, so ath9k can just indicate
support for this. Based on initial tests, this combination seems to
work fine.
Signed-off-by: NJouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -949,6 +949,7 @@ static void ath9k_set_hw_capab(struct ath_softc *sc, struct ieee80211_hw *hw)
 	hw->wiphy->flags |= WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL;
 	hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_5_10_MHZ;
 	hw->wiphy->flags |= WIPHY_FLAG_HAS_CHANNEL_SWITCH;
+	hw->wiphy->flags |= WIPHY_FLAG_AP_UAPSD;
 
 	hw->queues = 4;
 	hw->max_rates = 4;