Add a first test to validate the protocol:

- rtas/get-time-of-day compares the time
  from the guest with the time from the host.
Signed-off-by: NLaurent Vivier <lvivier@redhat.com>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>