[IA64-SGI] SN topology fix for large systems

There is an SN bug in sn_hwperf.c that affects systems with 1024n or 1024p.
The bug manifests itself 2 ways: IO interrupts are not always
targeted to the nearest node, and 2) the "cat /proc/sgi_sn/sn_topology"
commands fails with "cannot allocate memory".

The code is using the wrong macros for validating node numbers.

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