ath9k: fix beacon timer init on reset

SVN-Revision: 28169

package/mac80211/patches/585-ath9k_fix_beacon_timer.patch

@@ -0,0 +1,11 @@
+--- a/drivers/net/wireless/ath/ath9k/beacon.c
++++ b/drivers/net/wireless/ath/ath9k/beacon.c
+@@ -505,7 +505,7 @@ static void ath_beacon_config_ap(struct 
+ 	/* NB: the beacon interval is kept internally in TU's */
+ 	intval = TU_TO_USEC(conf->beacon_interval);
+ 	intval /= ATH_BCBUF;    /* for staggered beacons */
+-	nexttbtt = intval;
++	nexttbtt = roundup(ath9k_hw_gettsf32(ah) + TU_TO_USEC(FUDGE), intval);
+ 
+ 	/*
+ 	 * In AP mode we enable the beacon timers and SWBA interrupts to