nl80211: add new rssi event to indicate beacon loss

Tell userspace about beacon loss event.
This event doesn't replace the deauth/disassoc that
might come if the AP is not available.

The driver can send this event in order to hint
userspace what might follow (which in turn can
use it as roaming trigger).
Signed-off-by: NEliad Peller <eliad@wizery.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

include/linux/nl80211.h

@@ -2534,10 +2534,14 @@ enum nl80211_attr_cqm {
  *      configured threshold
  * @NL80211_CQM_RSSI_THRESHOLD_EVENT_HIGH: The RSSI is higher than the
  *      configured threshold
+ * @NL80211_CQM_RSSI_BEACON_LOSS_EVENT: The device experienced beacon loss.
+ *	(Note that deauth/disassoc will still follow if the AP is not
+ *	available. This event might get used as roaming event, etc.)
  */
 enum nl80211_cqm_rssi_threshold_event {
 	NL80211_CQM_RSSI_THRESHOLD_EVENT_LOW,
 	NL80211_CQM_RSSI_THRESHOLD_EVENT_HIGH,
+	NL80211_CQM_RSSI_BEACON_LOSS_EVENT,
 };