Accept response to any pending request, not just the last one. This
gives the Supplicant more time to reply since hostapd will now allow up
to three seconds for the reply to the first EAPOL-Key frame transmission
(and two seconds for the first retry and one second for the last) while
the previous version invalidated any old request immediately when
sending a retransmitted frame.
If the Supplicant replies to more than one request, only the first reply
to arrive at the Authenticator will be processed. As far as the
Supplicant is concerned, this behavior does not differ from the previous
one except for being less likely to cause unneeded retransmissions of
EAPOL-Key frames.
This can help in cases where power saving is used when the group key is
rekeyed or when there is excessive traffic on the channel that can delay
(or drop) EAPOL-Key frames.
We need to cancel the group key update for a STA if a reauthentication
request is received while the STA is in pending group key update. When
canceling the update, we will also need to make sure that the PTK Group Key
state machine ends up in the correct state (IDLE) to allow future updates
in case of WPA2.
