sgi-xp: add _sn2 suffix to a few variables

Add an '_sn2' suffix to some variables found in xpc_sn2.c.
Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>