wlantest used to ignore RSN/WPA/OSEN element in (Re)Association Request
frame if no Beacon frame had been seen from the AP before the
association exchange. This could result in not being able to derive keys
properly. Work around this by skipping that step if the BSS entry is not
yet complete.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>