message: camera: get rid of unneeded code
  In the case where we don't know about a parameter from the definition
  file, there is no point in trying to get it from the camera anyway. This
  is just an error.
diff: @@ -1244,25 +1244,11 @@ void CameraImpl::get_option_async(const std::string &setting_id,
  }
  } else {
  // If this still happens, we request the param, but also complain.
  - LogWarn() << "The param was probably outdated, trying to fetch it";
  - _parent->get_param_async(
  - setting_id,
  - [setting_id, this](bool success, MAVLinkParameters::ParamValue value_gotten) {
  - if (!success) {
  - LogWarn() << "Fetching the param failed";
  - return;
  - }
  - // We need to check again by the time this callback runs
  - if (!this->_camera_definition) {
  - return;
  + LogWarn() << "Setting '" << setting_id << "' not found.";
  + if (callback) {
  + Camera::Option no_option{};
  + callback(Camera::Result::ERROR, no_option);
  }
  - this->_camera_definition->set_setting(setting_id, value_gotten);
  - },
  - true);
  -
  - // At this point it might be a good idea to refresh but it's a bit scary
  - // as the stack keeps growing at this point.
  - // refresh_params();
  }
  }
  