ath9k: Enable TSF Out of Range Interrupt

This patch lays the groundwork for handling TSF Out of Range
interrupt, which will be used for power save later on.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/beacon.c b/drivers/net/wireless/ath9k/beacon.c
index 2e2ef35..390d510 100644
--- a/drivers/net/wireless/ath9k/beacon.c
+++ b/drivers/net/wireless/ath9k/beacon.c
@@ -753,6 +753,9 @@
 		if (bs.bs_sleepduration > bs.bs_dtimperiod)
 			bs.bs_sleepduration = bs.bs_dtimperiod;
 
+		/* TSF out of range threshold fixed at 1 second */
+		bs.bs_tsfoor_threshold = ATH9K_TSFOOR_THRESHOLD;
+
 		DPRINTF(sc, ATH_DBG_BEACON,
 			"tsf %llu "
 			"tsf:tu %u "