AP_UAVCAN: fix compilation when HAL_WITH_ESC_TELEM == 0

libraries/AP_UAVCAN/AP_UAVCAN.cpp

@@ -789,6 +789,7 @@ void AP_UAVCAN::handle_actuator_status(AP_UAVCAN* ap_uavcan, uint8_t node_id, co
  */
 void AP_UAVCAN::handle_ESC_status(AP_UAVCAN* ap_uavcan, uint8_t node_id, const ESCStatusCb &cb)
 {
+#if HAL_WITH_ESC_TELEM
     const uint8_t esc_index = cb.msg->esc_index;
 
     if (!is_esc_data_index_valid(esc_index)) {
@@ -806,6 +807,7 @@ void AP_UAVCAN::handle_ESC_status(AP_UAVCAN* ap_uavcan, uint8_t node_id, const E
         AP_ESC_Telem_Backend::TelemetryType::CURRENT
             | AP_ESC_Telem_Backend::TelemetryType::VOLTAGE
             | AP_ESC_Telem_Backend::TelemetryType::TEMPERATURE);
+#endif
 }
 
 bool AP_UAVCAN::is_esc_data_index_valid(const uint8_t index) {