sgi-xp: base xpc_rsvd_page's timestamp on jiffies

Change XPC's reserved page timestamp to be based on jiffies.

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>