This gets rid of potential warnings about buffer bounds errors. The earlier
code works fine, but it is not the cleanest way of using the struct wpa_ptk
definition for TK1/TK2.
The old version was using struct wpa_sm::bssid which is not necessarily
updated to point to the correct target address when doing over-the-air FT
since the address is used before the association has actually been
completed.
Transition. This fixes a potential issue where an incorrectly behaving AP
could send a group key update using the old (now invalid after reassociate)
PTK. This could also happen if there is a race condition between reporting
received EAPOL frames and association events.
