Revert "mac80211: in IBSS use the Auth frame to trigger STA reinsertion"

This reverts commit 6d810f10

In this way an IBSS station will not use the AUTH messages
to trigger a state reinitialisation anymore.

The behaviour was racy and was not working properly.
It has been introduced to help wpa_supplicant to support
IBSS/RSN, however all the logic is now getting moved into
wpa_s itself which will also be in charge of handling the
AUTH messages thanks to the mgmt frame registration.

If userspace does not register for receiving AUTH frames
then mac80211 will still reply by itself.

At the same time, the auth frame registration counter can be
removed since it is not needed anymore.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
[remove unused variable]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>