LinuxKPI: 802.11: implement ieee80211_beacon_loss()
Implement ieee80211_beacon_loss() similar to
ieee80211_connection_loss() with different state handling.
While here leave a comment in connection_loss() about the state
change argument.
Sponsored by: The FreeBSD Foundation
(cherry picked from commit bb81db90f7e00f56df9ea14132a54ee983e7177f)