ath9k: fix timeout on stopping rx dma

It seems that using ath9k_hw_stoppcurecv to stop rx dma is not enough.
When it's time to stop DMA, the PCU is still busy, so the rx enable
bit never clears.
Using ath9k_hw_abortpcurecv helps with getting rx stopped much faster,
with this change, I cannot reproduce the rx stop related WARN_ON anymore.
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Cc: stable@kernel.org
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -518,7 +518,7 @@ bool ath_stoprecv(struct ath_softc *sc)
 	bool stopped;
 
 	spin_lock_bh(&sc->rx.rxbuflock);
-	ath9k_hw_stoppcurecv(ah);
+	ath9k_hw_abortpcurecv(ah);
 	ath9k_hw_setrxfilter(ah, 0);
 	stopped = ath9k_hw_stopdmarecv(ah);