[IA64-SGI] fix the size of __sn_cnodeid_to_nasid

The __sn_cnodeid_to_nasid array was incorrectly sized at MAX_NUMNODES.
On a large system, this array could overflow.  The following patch
corrects this by defining it to MAX_COMPACT_NODES.

Signed-off-by: Dean Roe <roe@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>