virtio_ccw: future-proof finalize_features

We never negotiate revision > 1, but just to
make this code more likely to work when we do,
require VERSION_1 with any revision >= 1.

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