ath9k_hw: clean up register write buffering

Throughout the code, DISABLE_REGWRITE_BUFFER is always called right after
REGWRITE_BUFFER_FLUSH. Since that's unlikely to change any time soon, that
makes keeping those ops separate rather pointless, as it only increases
code size and line number counts.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
index 87dbb85..d558c51 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -70,19 +70,13 @@
 
 #define ENABLE_REGWRITE_BUFFER(_ah)					\
 	do {								\
-		if (AR_SREV_9271(_ah))					\
+		if (ath9k_hw_common(_ah)->ops->enable_write_buffer)	\
 			ath9k_hw_common(_ah)->ops->enable_write_buffer((_ah)); \
 	} while (0)
 
-#define DISABLE_REGWRITE_BUFFER(_ah)					\
-	do {								\
-		if (AR_SREV_9271(_ah))					\
-			ath9k_hw_common(_ah)->ops->disable_write_buffer((_ah)); \
-	} while (0)
-
 #define REGWRITE_BUFFER_FLUSH(_ah)					\
 	do {								\
-		if (AR_SREV_9271(_ah))					\
+		if (ath9k_hw_common(_ah)->ops->write_flush)		\
 			ath9k_hw_common(_ah)->ops->write_flush((_ah));	\
 	} while (0)