b43legacy: Avoid packet losses in the dma worker code

This patch addresses a bug in the dma worker code that keeps draining
packets even when the hardware queues are full. In such cases packets
can not be passed down to the device and are erroneusly dropped by the
code. It is based on commit bad6919469,
which fixes the same problem in b43.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43legacy/dma.h

@@ -150,8 +150,9 @@ struct b43legacy_dmaring {
 	enum b43legacy_dmatype type;
 	/* Boolean. Is this ring stopped at ieee80211 level? */
 	bool stopped;
-	/* Lock, only used for TX. */
-	spinlock_t lock;
+	/* The QOS priority assigned to this ring. Only used for TX rings.
+	 * This is the mac80211 "queue" value. */
+	u8 queue_prio;
 	struct b43legacy_wldev *dev;
 #ifdef CONFIG_B43LEGACY_DEBUG
 	/* Maximum number of used slots. */