ppc/pnv: set root port chassis and slot using Bus properties

ppc/pnv: set root port chassis and slot using Bus properties

For default root ports we have a way of accessing chassis and slot,
before root_port_realize(), via pnv_phb_attach_root_port(). For the
future user created root ports this won't be the case: we can't use
this helper because we don't have access to the PHB phb-id/chip-id
values.

In earlier patches we've added phb-id and chip-id to pnv-phb-root-bus
objects. We're now able to use the bus to retrieve them. The bus is
reachable for both user created and default devices, so we're changing
all the code paths. This also allow us to validate these changes with
the existing default devices.

Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-Id: <20220811163950.578927-4-danielhb413@gmail.com>