With our interests moving to other areas, Greg and myself no longer have
capacity to be regular reviewers of code for the powernv machine type, let
alone co-maintainers.  Additionally, not being IBM employees, we don't have
easy access to the hardware information we'd need for good review.

Therefore, remove our names as reviewers and/or co-maintainers of the
powernv machine type, and the related XIVE interrupt controller.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Acked-by: Cédric Le Goater <clg@kaod.org>