mISDN: fix possible memory leak in mISDN_dsp_element_register()

Afer commit 1fa5ae857bb1 ("driver core: get rid of struct device's
bus_id string array"), the name of device is allocated dynamically,
use put_device() to give up the reference, so that the name can be
freed in kobject_cleanup() when the refcount is 0.

The 'entry' is going to be freed in mISDN_dsp_dev_release(), so the
kfree() is removed. list_del() is called in mISDN_dsp_dev_release(),
so it need be initialized.

Fixes: 1fa5ae857bb1 ("driver core: get rid of struct device's bus_id string array")
Signed-off-by: Yang Yingliang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/isdn/mISDN/dsp_pipeline.c

···
 	if (!entry)
 		return -ENOMEM;
 
+	INIT_LIST_HEAD(&entry->list);
 	entry->elem = elem;
 
 	entry->dev.class = elements_class;
···
 	device_unregister(&entry->dev);
 	return ret;
 err1:
-	kfree(entry);
+	put_device(&entry->dev);
 	return ret;
 }
 EXPORT_SYMBOL(mISDN_dsp_element_register);