FST: Make FST peer connection check more permissive in hostapd

FST: Make FST peer connection check more permissive in hostapd

Modify the FST peer connection check so it won't skip peers without MB
IEs making it more permissive for peers that didn't provide MB IEs
during association request. This can be helpful, e.g., in cases where a
STA's interface connected before it was added to the FST group. This
allows the AP to receive FST Action frames and initiate session with a
STA via STA's interface that doesn't expose MB IEs.

The adjusted FST protocol is still safe, as it protects itself in many
other ways (checking band info and it's accordance to the interfaces,
Setup IDs, connection states of the interfaces involved, etc.)
effectively avoiding all types of invalid situations.

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