AP_Volz_Protocol: bugfix with scaling integer

[DjMixMasterDragon]

Bugfix to the recent Volz protocol implementation. motor_temp_deg and pcb_temp_deg are both defined as uint16_t which is valid pre-scaling (ie. receiving the message from the buffer) but with scaling being done below (range -49 to +204) this will need to account for signed values.

case CMD_ID::TEMPERATURE_RESPONSE:
      // Temperature is reported relative to -50 deg C
      telem.data[index].motor_temp_deg = -50 + cmd.arg1;
      telem.data[index].pcb_temp_deg = -50 + cmd.arg2;
      break;

[IamPete1]

@DjMixMasterDragon Well spotted, it not been cold enough for me too see this IRL. Have you been testing with hardware? How have you found the updated library? I have only been able to test on one model number.

The logging format type also need changing to match here:

ardupilot/libraries/AP_Volz_Protocol/AP_Volz_Protocol.cpp

Line 408 in 874d268

"QBffffffHH",

From H to h.