AP: Extend EAPOL-Key msg 1/4 retry workaround for changing SNonce

AP: Extend EAPOL-Key msg 1/4 retry workaround for changing SNonce

If the 4-way handshake ends up having to retransmit the EAPOL-Key
message 1/4 due to a timeout on waiting for the response, it is possible
for the Supplicant to change SNonce between the first and second
EAPOL-Key message 2/4. This is not really desirable due to extra
complexities it causes on the Authenticator side, but some deployed
stations are doing this.

This message sequence looks like this:
AP->STA: EAPOL-Key 1/4 (replay counter 1, ANonce)
AP->STA: EAPOL-Key 1/4 (replay counter 2, ANonce)
STA->AP: EAPOL-Key 2/4 (replay counter 1, SNonce 1)
AP->STA: EAPOL-Key 3/4 (replay counter 3, ANonce)
STA->AP: EAPOL-Key 2/4 (replay counter 2, SNonce 2)
followed by either:
STA->AP: EAPOL-Key 4/4 (replay counter 3 using PTK from SNonce 1)
or:
AP->STA: EAPOL-Key 3/4 (replay counter 4, ANonce)
STA->AP: EAPOL-Key 4/4 (replay counter 4, using PTK from SNonce 2)

Previously, Authenticator implementation was able to handle the cases
where SNonce 1 and SNonce 2 were identifical (i.e., Supplicant did not
update SNonce which is the wpa_supplicant behavior) and where PTK
derived using SNonce 2 was used in EAPOL-Key 4/4. However, the case of
using PTK from SNonce 1 was rejected ("WPA: received EAPOL-Key 4/4
Pairwise with unexpected replay counter" since EAPOL-Key 3/4 TX and
following second EAPOL-Key 2/4 invalidated the Replay Counter that was
used previously with the first SNonce).

This commit extends the AP/Authenticator workaround to keep both SNonce
values in memory if two EAPOL-Key 2/4 messages are received with
different SNonce values. The following EAPOL-Key 4/4 message is then
accepted whether the MIC has been calculated with the latest SNonce (the
previously existing behavior) or with the earlier SNonce (the new
extension). This makes 4-way handshake more robust with stations that
update SNonce for each transmitted EAPOL-Key 2/4 message in cases where
EAPOL-Key message 1/4 needs to be retransmitted.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>