[IA64-SGI] Altix SN topology support for new chipsets and pci topology

please accept this patch to the Altix SN platform topology export
interface to support new chipsets and to export PCI topology.

This follows on top of Jack Steiner's patch dated March 1st
("New chipset support for SN platform").

Signed-off-by: Mark Goodwin <markgw@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>