mac80211: fix CSA handling timer

The time until the channel switch is in TU,
not in milliseconds, so use TU_TO_EXP_TIME()
to correctly program the timer.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -813,8 +813,7 @@ void ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 		ieee80211_queue_work(&sdata->local->hw, &ifmgd->chswitch_work);
 	else
 		mod_timer(&ifmgd->chswitch_timer,
-			  jiffies +
-			  msecs_to_jiffies(sw_elem->count *
+			  TU_TO_EXP_TIME(sw_elem->count *
 					 cbss->beacon_interval));
 }