mac80211_hwsim: Make sure beacon_timer gets deleted

It was possible to trigger a kernel panic because beacon_timer may not
have been deleted in all cases when the kernel module was removed while
hostapd was still running.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -290,6 +290,7 @@ static void mac80211_hwsim_stop(struct ieee80211_hw *hw)
 {
 	struct mac80211_hwsim_data *data = hw->priv;
 	data->started = 0;
+	del_timer(&data->beacon_timer);
 	printk(KERN_DEBUG "%s:%s\n", wiphy_name(hw->wiphy), __func__);
 }