fix the linking issues when slave id option is disabled v1

test/serial/mb_serial_master/main/master.c

@@ -304,7 +304,7 @@ static void master_operation_func(void *arg)
     const mb_parameter_descriptor_t* param_descriptor = NULL;
 
     ESP_LOGI(TAG, "Start modbus test...");
-
+#if CONFIG_FMB_CONTROLLER_SLAVE_ID_SUPPORT
     // Command - 17 (0x11) Report Slave ID (Serial Line only)
     // The command contains vendor specific data and should be interpreted accordingly.
     // This version of command handler needs to define the maximum number
@@ -324,6 +324,7 @@ static void master_operation_func(void *arg)
     } else {
         ESP_LOG_BUFFER_HEX_LEVEL("SLAVE_INFO", (void*)info_buf, sizeof(info_buf), ESP_LOG_WARN);
     }
+#endif
 
     for(uint16_t retry = 0; retry <= MASTER_MAX_RETRY && (!alarm_state); retry++) {
         // Read all found characteristics from slave(s)

test/serial/mb_serial_slave/main/slave.c

@@ -230,6 +230,7 @@ void app_main(void)
     ESP_LOGI(TAG, "Modbus slave stack initialized.");
     ESP_LOGI(TAG, "Start modbus test...");
 
+#if CONFIG_FMB_CONTROLLER_SLAVE_ID_SUPPORT
     uint8_t ext_data[] = {0x11, 0x22, 0x33, 0x44, 0x55};
     // This is the way to set Slave ID fields to retrieve it by master using report slave ID command.
     int err = eMBSetSlaveID(comm_info.slave_addr, true, (uint8_t *)&ext_data, sizeof(ext_data));
@@ -238,6 +239,7 @@ void app_main(void)
     } else {
         ESP_LOGE("SET_SLAVE_ID", "Set slave ID fail, err=%d.", err);
     }
+#endif
 
     // The cycle below will be terminated when parameter holdingRegParams.dataChan0
     // incremented each access cycle reaches the CHAN_DATA_MAX_VAL value.