AP: Fix disconnect from EAPOL state machine handling

AP: Fix disconnect from EAPOL state machine handling

An earlier change to extend ap_sta_disconnect() to cover MLD cases ended
up calling ieee802_1x_free_station() from the step function in the EAPOL
authenticator state machine in case of EAP timeout and by doing so,
ended up leaving the EAPOL state machine operations continuing to be run
on freed memory.

Fix this by leaving the EAPOL state machine allocated when going through
all the other ap_sta_disconnect() steps so that the possible ongoing
operations can be finished safely before freeing memory. Actual freeing
of the state machine happens when freeing the full STA entry in the same
way that was used previously.

Fixes: 01677c47fb13 ("AP: Support disconnect with MLD")
Signed-off-by: Jouni Malinen <j@w1.fi>