ath9k: fix PS-Poll reception on AR9160 and earlier

I can't find any valid reason for not setting the ATH9K_RX_FILTER_PSPOLL
flag on older hardware and neither the documentation nor the reference
code mention any reason for excluding older hardware here.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -426,9 +426,7 @@ u32 ath_calcrxfilter(struct ath_softc *sc)
 	else
 		rfilt |= ATH9K_RX_FILTER_BEACON;
 
-	if ((AR_SREV_9280_20_OR_LATER(sc->sc_ah) ||
-	    AR_SREV_9285_12_OR_LATER(sc->sc_ah)) &&
-	    (sc->sc_ah->opmode == NL80211_IFTYPE_AP) &&
+	if ((sc->sc_ah->opmode == NL80211_IFTYPE_AP) ||
 	    (sc->rx.rxfilter & FIF_PSPOLL))
 		rfilt |= ATH9K_RX_FILTER_PSPOLL;