PHB hotplug will bring more users for it. Let's define it along with
the PHB defines from which it is derived for simplicity.
While here fix a misleading comment about manual placement, which was
abandoned with 30b3bc5aa9f4.
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
1da85c2ae6