virtio_ccw: finalize_features error handling

We previously tried to use device even if finalize_features failed, but
that's wrong since driver and device are now out of sync.

Fail probe if we detect failures during finalize_features.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>