[IA64] Update Altix nofault code

Montecito and Montvale behaves slightly differently than previous
Itanium processors, resulting in the MCA due to a failed PIO read
to sometimes surfacing outside the nofault code.  This code is
based on discussions with Intel CPU architects and verified at
customer sites.

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