Finally offering the possibility to enable SVQ from the command line.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>