[IA64-SGI] SN SAL call to inject memory errors

The SGI Altix SAL provides an interface for modifying
the ECC on memory to create memory errors.  The SAL call
can be used to inject memory errors for testing MCA recovery
code.

Signed-off-by: Russ Anderson <(rja@sgi.com)>
Signed-off-by: Tony Luck <tony.luck@intel.com>