ath9k: block new AMPDU sessions if SC_OP_TXAGGR is not set

This makes further tx path cleanups easier
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -1979,6 +1979,9 @@ static int ath9k_ampdu_action(struct ieee80211_hw *hw,
 	case IEEE80211_AMPDU_RX_STOP:
 		break;
 	case IEEE80211_AMPDU_TX_START:
+		if (!(sc->sc_flags & SC_OP_TXAGGR))
+			return -EOPNOTSUPP;
+
 		ath9k_ps_wakeup(sc);
 		ret = ath_tx_aggr_start(sc, sta, tid, ssn);
 		if (!ret)