backlight: 88pm860x_bl: fix error handling in pm860x_backlight_probe

This patch  properly unregisters a previously registered backlight device object
in error handling
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

drivers/video/backlight/88pm860x_bl.c

@@ -267,6 +267,7 @@ static int pm860x_backlight_probe(struct platform_device *pdev)
 	backlight_update_status(bl);
 	return 0;
 out:
+	backlight_device_unregister(bl);
 	kfree(data);
 	return ret;
 }