ath9k: fix tx status reporting

This is a backport of upstream commit: e8c6342d989e241513baeba4b05a04b6b1f3bc8b

This patch fixes a bug in ath9k's tx status check, which
caused mac80211 to consider regularly transmitted unicast frames
as un-acked.

When checking the ts_status field for errors, it needs to be masked
with ATH9K_TXERR_FILT, because this field also contains other fields
like ATH9K_TX_ACKED.

Without this patch, AP mode is pretty much unusable, as hostapd
checks the ACK status for the frames that it injects.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

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

@@ -2020,7 +2020,7 @@ static void ath_tx_processq(struct ath_softc *sc, struct ath_txq *txq)
 		if (bf_isaggr(bf))
 			txq->axq_aggr_depth--;
 
-		txok = (ds->ds_txstat.ts_status == 0);
+		txok = !(ds->ds_txstat.ts_status & ATH9K_TXERR_FILT);
 		txq->axq_tx_inprogress = false;
 		spin_unlock_bh(&txq->axq_lock);