AP_BoardConfig: fixed build with logging disabled

fixes CubeOrange-periph build

libraries/AP_BoardConfig/IMU_heater.cpp

@@ -81,6 +81,7 @@ void AP_BoardConfig::set_imu_temp(float current)
         heater.output = constrain_float(heater.output, 0, 100);
     }
 
+#if HAL_LOGGING_ENABLED
     if (now - heater.last_log_ms >= 1000) {
 // @LoggerMessage: HEAT
 // @Description: IMU Heater data
@@ -98,6 +99,8 @@ void AP_BoardConfig::set_imu_temp(float current)
                            heater.output);
         heater.last_log_ms = now;
     }
+#endif // HAL_LOGGING_ENABLED
+
 #if 0
     gcs().send_text(MAV_SEVERITY_INFO, "Heater: Out=%.1f Temp=%.1f",
                     double(heater.output),