[IA64] discontig.c: fixup pxm_to_nid_map

[IA64] discontig.c: fixup pxm_to_nid_map

I'd like to be able to use pxm_to_nid_map in several places to
discover proximity domain to node id associations.  Unfortunately, after
reassign_cpu_only_nodes() plays with the node space, the pxm_to_nid_map
doesn't necessarily reflect reality.  This fixes up the table so it's
still valid.  Note that nid_to_pxm_map is still potentially broken, but
has a one-to-many problem if the above function combines several
proximity domains into a single node.  Thanks to Bob Picco for the base
patch.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>