HS 2.0: Generate AssocReq OSEN IE based on AP advertisement

HS 2.0: Generate AssocReq OSEN IE based on AP advertisement

Parse the OSEN IE from the AP to determine values used in the AssocReq
instead of using hardcoded cipher suites. This is needed to be able to
set the group cipher based on AP advertisement now that two possible
options exists for this (GTK_NOT_USED in separate OSEN BSS; CCMP or
GTK_NOT_USED in shared BSS case). Furthermore, this is a step towards
allowing other ciphers than CCMP to be used with OSEN.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>