ath9k: Make DMA warning in ath_stoprecv WARN_ON_ONCE.

This decreases spammage in the log.  A single line message
will still be printed, so users can be aware that problem
exists.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Acked-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 70f3fa6..3f8b2e3 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -528,8 +528,12 @@
 		sc->rx.rxlink = NULL;
 	spin_unlock_bh(&sc->rx.rxbuflock);
 
-	ATH_DBG_WARN(!stopped, "Could not stop RX, we could be "
-		     "confusing the DMA engine when we start RX up\n");
+	if (unlikely(!stopped)) {
+		ath_err(ath9k_hw_common(sc->sc_ah),
+			"Could not stop RX, we could be "
+			"confusing the DMA engine when we start RX up\n");
+		ATH_DBG_WARN_ON_ONCE(!stopped);
+	}
 	return stopped;
 }