In case of beacon_loss with IEEE80211_HW_CONNECTION_MONITOR
device, mac80211 probes the ap (and disconnects on timeout)
but ignores the ack.

If we already got an ack, there's no reason to continue
disconnecting. this can help devices that supports
IEEE80211_HW_CONNECTION_MONITOR only partially (e.g. take
care of keep alives, but does not probe the ap.

In case the device wants to disconnect without probing,
it can just call ieee80211_connection_loss.
Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>