EAP-FAST: Allow A-ID and A-ID-Info to be configured separately

Changed EAP-FAST configuration to use separate fields for A-ID and
A-ID-Info (eap_fast_a_id_info) to allow A-ID to be set to a fixed
16-octet len binary value for better interoperability with some peer
implementations; eap_fast_a_id is now configured as a hex string.