Restructure the pcibios_root_bridge_prepare() as the preparation for
supporting cases when no real ACPI device is related to the PCI host
bridge.
No functional change.
Link: https://lore.kernel.org/r/20210726180657.142727-4-boqun.feng@gmail.com
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
b424d4d426