ath9k_hw: optimize interrupt mask changes

OProfile showed that ath9k was spending way too much time in
ath9k_hw_set_interrupts. Since most of the interrupt mask changes only
need to globally enable/disable interrupts, it makes sense to split
this part into separate functions, replacing all calls to
ath9k_hw_set_interrupts(ah, 0) with ath9k_hw_disable_interrupts(ah).

ath9k_hw_set_interrupts(ah, ah->imask) only gets changed to
ath9k_hw_enable_interrupts(ah), whenever ah->imask was not changed
since the point where interrupts were disabled.

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/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 19891e7..333da7b 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -503,7 +503,7 @@
 
 	/* Set the computed AP beacon timers */
 
-	ath9k_hw_set_interrupts(ah, 0);
+	ath9k_hw_disable_interrupts(ah);
 	ath9k_beacon_init(sc, nexttbtt, intval);
 	sc->beacon.bmisscnt = 0;
 	ath9k_hw_set_interrupts(ah, ah->imask);
@@ -638,7 +638,7 @@
 
 	/* Set the computed STA beacon timers */
 
-	ath9k_hw_set_interrupts(ah, 0);
+	ath9k_hw_disable_interrupts(ah);
 	ath9k_hw_set_sta_beacon_timers(ah, &bs);
 	ah->imask |= ATH9K_INT_BMISS;
 	ath9k_hw_set_interrupts(ah, ah->imask);
@@ -686,7 +686,7 @@
 
 	/* Set the computed ADHOC beacon timers */
 
-	ath9k_hw_set_interrupts(ah, 0);
+	ath9k_hw_disable_interrupts(ah);
 	ath9k_beacon_init(sc, nexttbtt, intval);
 	sc->beacon.bmisscnt = 0;
 	ath9k_hw_set_interrupts(ah, ah->imask);