[IA64-SGI] fix unaligned memory access in snsc_event.c

It's been pointed out that environmental events from the system
controllers on Altix machines cause the kernel to complain about
unaligned memory accesses.  This turns out to be because
"be32_to_cpup()" didn't do everything I thought/hoped it did.
I've added calls to pull the offending integers out of the
buffers using get_unaligned() before feeding them to
be32_to_cpup().

Signed-off-by: Greg Howard <ghoward@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>