[IA64-SGI] fix SGI Altix tioce_reserve_m32() bug

The following patch fixes a bug in the SGI Altix tioce_reserve_m32()
code.  The bug was that we could walking past the end of the CE ASIC
32/40bit PMU ATE Buffer, resulting in a PIO Reply Error.

Signed-off-by: Mike Habeck <habeck@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>