tools/vm/page-types.c: cleanups

Compiling page-type.c with a recent compiler produces many warnings,
mostly related to signed/unsigned comparisons.  This patch cleans up most
of them.

One remaining warning is about an unused parameter.  The <compiler.h> file
doesn't define a __unused macro (or the like) yet.  This can be addressed
later.

Signed-off-by: Ulrich Drepper <drepper@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>