zdtm:fifo: check that read only fifo descriptor is restored

* Create fifo and two descriptors rw and ro
* Write data and close rw descriptor
* Suspend/resume
* Read data from ro descriptor

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>