ath9k: fix DMA stop sequence for AR9003+

commit 300f77c0 upstream.

AR93xx and newer needs to stop rx before tx to avoid getting the DMA
engine or MAC into a stuck state.
This should reduce/fix the occurence of "Failed to stop Tx DMA" logspam.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

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

@@ -205,11 +205,13 @@ static bool ath_prepare_reset(struct ath_softc *sc)
 	ath_stop_ani(sc);
 	ath9k_hw_disable_interrupts(ah);
 
-	if (!ath_drain_all_txq(sc))
-		ret = false;
-
-	if (!ath_stoprecv(sc))
-		ret = false;
+	if (AR_SREV_9300_20_OR_LATER(ah)) {
+		ret &= ath_stoprecv(sc);
+		ret &= ath_drain_all_txq(sc);
+	} else {
+		ret &= ath_drain_all_txq(sc);
+		ret &= ath_stoprecv(sc);
+	}
 
 	return ret;
 }