Allow SNonce update after sending EAPOL-Key 3/4 if 1/4 was retransmitted
Some supplicant implementations (e.g., Windows XP WZC) update SNonce for
each EAPOL-Key 2/4. This breaks the workaround on accepting any of the
pending requests, so allow the SNonce to be updated even if we have
already sent out EAPOL-Key 3/4.
While the issue was made less likely to occur when the retransmit
timeout for the initial EAPOL-Key msg 1/4 was increased to 1000 ms,
this fixes the problem even if that timeout is not long enough.