ath9k_hw: clean up tx completion interrupt handling

TXQ_FLAG_TXOKINT_ENABLE and TXQ_FLAG_TXERRINT_ENABLE are always set and
used together, and they share the same bitmask in enum ath9k_tx_queue_flags.
Simplify the code that tests for these flags.

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/mac.h b/drivers/net/wireless/ath/ath9k/mac.h
index 11dbd14..6476d907 100644
--- a/drivers/net/wireless/ath/ath9k/mac.h
+++ b/drivers/net/wireless/ath/ath9k/mac.h
@@ -583,8 +583,7 @@
 #define ATH9K_WME_UPSD	4
 
 enum ath9k_tx_queue_flags {
-	TXQ_FLAG_TXOKINT_ENABLE = 0x0001,
-	TXQ_FLAG_TXERRINT_ENABLE = 0x0001,
+	TXQ_FLAG_TXINT_ENABLE = 0x0001,
 	TXQ_FLAG_TXDESCINT_ENABLE = 0x0002,
 	TXQ_FLAG_TXEOLINT_ENABLE = 0x0004,
 	TXQ_FLAG_TXURNINT_ENABLE = 0x0008,