ath9k_hw: Add function to configure tx status ring buffer

Also reset tx status ring suring chip reset.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/reg.h b/drivers/net/wireless/ath/ath9k/reg.h
index 2ca478c..ff89140 100644
--- a/drivers/net/wireless/ath/ath9k/reg.h
+++ b/drivers/net/wireless/ath/ath9k/reg.h
@@ -383,6 +383,9 @@
 #define AR_Q9_TXDP           0x0824
 #define AR_QTXDP(_i)    (AR_Q0_TXDP + ((_i)<<2))
 
+#define AR_Q_STATUS_RING_START	0x830
+#define AR_Q_STATUS_RING_END	0x834
+
 #define AR_Q_TXE             0x0840
 #define AR_Q_TXE_M           0x000003FF