message: telemetry: workaround for PX4
  For some reason PX4 doesn't set enabled for GPS, sadly.
diff: @@ -1179,8 +1179,9 @@ void TelemetryImpl::process_sys_status(const mavlink_message_t& message)
  bool TelemetryImpl::sys_status_present_enabled_health(
  const mavlink_sys_status_t& sys_status, MAV_SYS_STATUS_SENSOR flag)
  {
  + // FIXME: it doesn't look like PX4 sets enabled for GPS
  return (sys_status.onboard_control_sensors_present & flag) != 0 &&
  - (sys_status.onboard_control_sensors_enabled & flag) != 0 &&
  + // (sys_status.onboard_control_sensors_enabled & flag) != 0 &&
  (sys_status.onboard_control_sensors_health & flag) != 0;
  }
  