Private plugin are considered those whose name ends with "private".
Avoid being misleading, i.e. do not declare the plugin dump as successful.

Change-Id: Id181d3a09dc9c4895f6566e22ad670435bd5a7f8
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
Reviewed-by: Tim Jenssen <tim.jenssen@theqtcompany.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@theqtcompany.com>