These hunks got dropped off mysteriously during the rebasing of my
virtio-serial series. Thanks go to Markus for noticing it.

Without these fixes, -virtioconsole doesn't actually have any effect.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reported-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>