https://bugzilla.redhat.com/show_bug.cgi?id=1572491

Commit id '78661cb1' added a physical output, but failed to update
the schema resulting in a failure from virt-xml-validate.

While at it - update the storagevolschemadata for the output.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
ACKed-by Michal Privoznik <mprivozn@redhat.com>