platform/chrome: unregister platform driver/device when module exit

We have registered platform driver and device when module
init, and need unregister them when module exit.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NOlof Johansson <olof@lixom.net>

drivers/platform/chrome/chromeos_laptop.c

@@ -511,6 +511,9 @@ static void __exit chromeos_laptop_exit(void)
 		i2c_unregister_device(tp);
 	if (ts)
 		i2c_unregister_device(ts);
+
+	platform_device_unregister(cros_platform_device);
+	platform_driver_unregister(&cros_platform_driver);
 }
 
 module_init(chromeos_laptop_init);