The primary Xen console is special. The guest's side is set up for it by
the toolstack automatically and not by the standard PV init sequence.
Accordingly, its *frontend* doesn't appear in …/device/console/0 either;
instead it appears under …/console in the guest's XenStore node.
To allow the Xen console driver to override the frontend path for the
primary console, add a method to the XenDeviceClass which can be used
instead of the standard xen_device_get_frontend_path()
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>