target/ppc, hw/ppc: Change maintainers

target/ppc, hw/ppc: Change maintainers

As our day jobs and interests have moved onto other things, Greg and I have
been struggling to keep on top of maintainership of target/ppc and
associated pieces like the pseries and powernv machine types, with their
platform specific devices.

We've therefore discussed and plan to transfer maintainership to Cédric Le
Goater (primary) and Daniel Henrique Barboza (backup).  Cédric and Daniel
have been actively contributing to the area for some time, and they're
supported in this by their current employer, IBM, who has an obvious
interest in the platform.

Greg and I do plan to stay around in some capacity for at least the next
6 months, providing reviews and advice to assist the new maintainers into
the role.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Acked-by: Cédric Le Goater <clg@kaod.org>