ath9k: remove a redundant call to ath9k_hw_gettsf32

When the timer_next argument to ath9k_gen_timer_start is behind the tsf value,
tsf + timer_period is used, which is what ath_btcoex_period_timer was setting
it to.
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/gpio.c

@@ -310,10 +310,8 @@ static void ath_btcoex_period_timer(unsigned long data)
 
 		timer_period = is_btscan ? btcoex->btscan_no_stomp :
 					   btcoex->btcoex_no_stomp;
-		ath9k_gen_timer_start(ah,
-				      btcoex->no_stomp_timer,
-				      (ath9k_hw_gettsf32(ah) +
-				       timer_period), timer_period * 10);
+		ath9k_gen_timer_start(ah, btcoex->no_stomp_timer, 0,
+				      timer_period * 10);
 		btcoex->hw_timer_enabled = true;
 	}