In order to be able to hotplug and use the virtio-blk-ccw for kata. Each device needs to be identified by a device number. In this way, it's possible to determine which device number can be assigned to the hotplugged virtio-blk-ccw. This PR extends govmm to ba able to assign a devno to each device and it adds the virtio-blk-ccw device.

Main track issue for kata is kata-containers/runtime#1153