[IA64] Update arch/ia64/configs/* s/SLAB/SLUB/

The slab allocator was changed in 2.6.23 to default to SLUB. However,
the config files in arch/ia64/configs still use SLAB. Switch them to SLUB.

Added same change to arch/ia64/defconfig ... Tony

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>