[sensors][mac] Make sure to update the sensor value when initializing the sensor.

device/generic_sensor/platform_sensor_ambient_light_mac.h

Index: device/generic_sensor/platform_sensor_ambient_light_mac.h
diff --git a/device/generic_sensor/platform_sensor_ambient_light_mac.h b/device/generic_sensor/platform_sensor_ambient_light_mac.h
index bf5c070744cc8a4405f8d2402818799103288d16..32f965d3f9b1aed882a121abbbf3b5990cbfc0df 100644
--- a/device/generic_sensor/platform_sensor_ambient_light_mac.h
+++ b/device/generic_sensor/platform_sensor_ambient_light_mac.h
@@ -40,9 +40,9 @@ class PlatformSensorAmbientLightMac : public PlatformSensor {
   bool CheckSensorConfiguration(
       const PlatformSensorConfiguration& configuration) override;
   PlatformSensorConfiguration GetDefaultConfiguration() override;
-  void UpdateReading(uint64_t lux_values[2]);
 
  private:
+  bool ReadAndUpdate();
   static void IOServiceCallback(void* context,
                                 io_service_t service,
                                 natural_t message_type,