ppc/pnv: add PHB3 bus init helper

The PnvPHB3 bus init consists of initializing the pci_io and pci_mmio
regions, registering it via pci_register_root_bus() and then setup the
iommu.

We'll want to init the bus from outside pnv_phb3.c when the bus is
removed from the PnvPHB3 device and put into a new parent PnvPHB device.
The new pnv_phb3_bus_init() helper will be used by the parent to init
the bus when using the PHB3 backend.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-Id: <20220624084921.399219-2-danielhb413@gmail.com>
2 files changed