tests/boot-serial: Check the 40p machine, too

tests/boot-serial: Check the 40p machine, too

The "40p" machine is using the Open Hack'Ware BIOS, just like the "prep"
machine, so we can test it accordingly with the boot-serial tester, too.
While we're at it, also change the strings that we are using for the
"prep" machine, so that this test now also checks some CLI parameters.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>