siox: fix possible memory leak in siox_device_add()

In the Linux kernel, the following vulnerability has been resolved: siox: fix possible memory leak in siox_device_add() If device_register() returns error in siox_device_add(), the name allocated by dev_set_name() need be freed. As comment of device_register() says, it should use put_device() to give up the reference in the error path. So fix this by calling put_device(), then the name can be freed in kobject_cleanup(), and sdevice is freed in siox_device_release(), set it to null in error path.