cfg80211: allow AID/listen interval changes for unassociated station

Currently, cfg80211 rejects updates of AID and listen interval parameters
for existing entries. This information is known only at association stage
and as a result it's impossible to update entries that were added
unassociated.
Fix this by allowing updates of these properies for stations that the
driver (or mac80211) assigned unassociated state.

This then fixes mac80211's use of NL80211_FEATURE_FULL_AP_CLIENT_STATE.

Signed-off-by: Ayala Beker <ayala.beker@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>