This fixes representation of the 'acpi_firmware' config in the Xen
driver, which repesents a concatenation of tables of any type.
Use of 'type=slic' is accepted on input for backwards compatibility.
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>