This enables the correct generation of bootdevice fw paths for in-built IDE
and virtio-pci-blk devices suitable for OpenBIOS.
Note we also set the MachineClass ignore_boot_device_suffixes property to true
to allow the correct customisation of the disk node names as required.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>