[IA64] uncached allocator: use generic (not sn2 specific) functions

Change sn2-specific calls into generic functions.  Without this change
the uncached allocator will not work on non-sn2 platforms.

Signed-off-by: Greg Edwards <edwardsg@sgi.com>
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>