Revert "ath9k: Calculate sleep duration"

This reverts commit 09ebb810.

ath9k_hw_set_sta_beacon_timers() configures AR_TIM_PERIOD with
the beacon interval. Before this commit, the sleepduration was
never greater than the beacon interval. But now, the behavior
has changed. For example, with an AP that uses a beacon interval of 100:

ath: phy9: next beacon 61128704
ath: phy9: beacon period 204800
ath: phy9: DTIM period 204800

If the sleepduration is calculated based on the listen time, then
the bmiss threshold should also be changed since the HW would
be in sleep state for a longer time, but that is not done currently.

To avoid configuring a higher beacon interval based on the sleepduration,
revert to the original behavior. Power consumption is not a
problem since PS is disabled in ath9k anyway.

Cc: stable@vger.kernel.org
Cc: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: NSujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/common-beacon.c

@@ -57,7 +57,7 @@ int ath9k_cmn_beacon_config_sta(struct ath_hw *ah,
 				 struct ath9k_beacon_state *bs)
 {
 	struct ath_common *common = ath9k_hw_common(ah);
-	int dtim_intval, sleepduration;
+	int dtim_intval;
 	u64 tsf;
 
 	/* No need to configure beacon if we are not associated */
@@ -75,7 +75,6 @@ int ath9k_cmn_beacon_config_sta(struct ath_hw *ah,
 	 * last beacon we received (which may be none).
 	 */
 	dtim_intval = conf->intval * conf->dtim_period;
-	sleepduration = ah->hw->conf.listen_interval * conf->intval;
 
 	/*
 	 * Pull nexttbtt forward to reflect the current
@@ -113,7 +112,7 @@ int ath9k_cmn_beacon_config_sta(struct ath_hw *ah,
 	 */
 
 	bs->bs_sleepduration = TU_TO_USEC(roundup(IEEE80211_MS_TO_TU(100),
-						  sleepduration));
+						  conf->intval));
 	if (bs->bs_sleepduration > bs->bs_dtimperiod)
 		bs->bs_sleepduration = bs->bs_dtimperiod;