[IA64-SGI] - Reduce overhead of reading sn_topology

MPI programs using certain debug options have a long
startup time. This was traced to a "vmalloc/vfree" in
the code that reads /proc/sgi_sn/sn_topology. On large
systems, vfree requires an IPI to all cpus to do TLB
purging.

Replace the vmalloc/vfree with kmalloc/kfree. Although
the size of the structure being allocated is unknown, it
will not not exceed 96 bytes.

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