Pass an error object to prepare for migration to VFIO-PCI realize.
For the time being let's just simply report the error in
vfio platform's vfio_base_device_init(). A subsequent patch will
duly propagate the error up to vfio_platform_realize.
Signed-off-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>