Placate coverity CID #1542424, #152423, #152422) (#5168)

Placate coverity CID #1542424, #152423, #152422) (#5168)

Currently, three functions mark requests as fake. That involves
calling fr_pair_value_from_str() with the string being "127.0.0.1".
Coverity notices that fr_pair_value_from_str() returns a value
that isn't checked.

 * setup_fake_request() nominally returns an int, but it always
   returns zero, and no caller actuallly checks its return value.
 * The other functions, chbind_process() and eap_fast_eap_payload(),
   return fr_radius_packet_code_t, and it's not clear which
   fr_radius_packet_code_t makes sense in this case.

So... we cast the fr_pair_value_from_str() calls to void.