Replace the usage of eap_send_response() in the method implementations
with a new eap_method_respond that skips the redundant "type" parameter.
The new eap_send_packet is used inside eap_method_respond and will be
reused for sending request packets in authenticator side EAP methods.
The identity retrieved from simauth was required to include the
prefix for SIM/AKA/AKA', but in reality a real SIM would not
include that prefix in the IMSI. Now the correct prefix is
prepended onto the identity depending on the EAP method.
If the SQN in AUTN is incorrect the simauth module will return
the AUTS parameter, which is sent back to the server and the
servers SQN number is updated.
The EAP-method's .probe methods only checked the method name so do that
in eap.c instead and allocate method state in .load_settings. Rename
method's .remove method to .free to improve the naming.
This EAP method uses nearly all the logic from EAP-AKA. The major
difference is it uses the new key derivation functions for AKA' as
well as the SHA256 MAC calculation.
EAP-AKA' uses SHA256 rather than SHA1 to generate the packet MAC's.
This updates the derive MAC API to take the EAP method type and
correctly use the right SHA variant to derive the MAC.
