ath9k_htc: add new WMI_REG_RMW_CMDID command

Since usb bus add extra delay on each request, a command
with read + write requests is too expensive. We can dramtically
reduce usb load by moving this command to firmware.

In my tests, this patch will reduce channel scan time
for about 5-10 seconds.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath9k/hw.h

@@ -100,6 +100,18 @@
 			(_ah)->reg_ops.write_flush((_ah));	\
 	} while (0)
 
+#define ENABLE_REG_RMW_BUFFER(_ah)					\
+	do {								\
+		if ((_ah)->reg_ops.enable_rmw_buffer)	\
+			(_ah)->reg_ops.enable_rmw_buffer((_ah)); \
+	} while (0)
+
+#define REG_RMW_BUFFER_FLUSH(_ah)					\
+	do {								\
+		if ((_ah)->reg_ops.rmw_flush)		\
+			(_ah)->reg_ops.rmw_flush((_ah));	\
+	} while (0)
+
 #define PR_EEP(_s, _val)						\
 	do {								\
 		len += scnprintf(buf + len, size - len, "%20s : %10d\n",\