mac80211: fix missing sta_lock in __sta_info_destroy

Since my commit 34e89507
("mac80211: allow station add/remove to sleep") there is
a race in mac80211 when it clears the TIM bit because a
sleeping station disconnected, the spinlock isn't held
around the relevant code any more. Use the right API to
acquire the spinlock correctly.

Cc: stable@kernel.org [2.6.34+]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/sta_info.c

@@ -665,7 +665,7 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
 		BUG_ON(!sdata->bss);
 
 		atomic_dec(&sdata->bss->num_sta_ps);
-		__sta_info_clear_tim_bit(sdata->bss, sta);
+		sta_info_clear_tim_bit(sta);
 	}
 
 	local->num_sta--;