Unvalidated `wire_format` parameter for the `b200mini` receiver operating in the mode `swept_center_frequency`

[jcfitzpatrick12]

For configs with the b200mini receiver:

• In the swept_center_frequency mode, the wire_format parameter accepts any value, e.g.
  spectre create config -t mre -r b200mini -m swept_center_frequency -p wire_format=invalid
  (No error is raised.)

• In the fixed_center_frequency mode, wire_format is correctly validated and must be one of sc8, sc12, or sc16.
  Invalid values (e.g. asdasdasd) result in a validation error.

The desired behaviour is that both modes should enforce allowed wire_format values, rejecting invalid input with a validation error.