ia64/PCI/ACPI: Use common interface to support PCI host bridge

Use common interface to simplify PCI host bridge implementation.

Tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>