[IA64-SGI] - Pass OS logical cpu number to the SN prom (bios)

Pass the OS logical cpu number to the PROM. This allows PROM
to log the OS logical cpu number in error records viewed thru POD.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>