AP/GO interface teardown optimization

This commit adds an option to optimize AP teardown by leaving the
deletion of keys (including group keys) and stations to the driver.

This optimization option should be used if the driver supports stations
and keys removal when stopping an AP.

For example, the optimization option will always be used for cfg80211
drivers since cfg80211 shall always remove stations and keys when
stopping an AP (in order to support cases where the AP is disabled
without the knowledge of wpa_supplicant/hostapd).

Signed-off-by: Moshe Benji <moshe.benji@intel.com>

src/ap/hostapd.h

@@ -273,6 +273,12 @@ struct hostapd_iface {
 	unsigned int wait_channel_update:1;
 	unsigned int cac_started:1;
 
+	/*
+	 * When set, indicates that the driver will handle the AP
+	 * teardown: delete global keys, station keys, and stations.
+	 */
+	unsigned int driver_ap_teardown:1;
+
 	int num_ap; /* number of entries in ap_list */
 	struct ap_info *ap_list; /* AP info list head */
 	struct ap_info *ap_hash[STA_HASH_SIZE];