x86, mm: Correct the implementation of is_untracked_pat_range()

The semantics the PAT code expect of is_untracked_pat_range() is "is
this range completely contained inside the untracked region."  This
means that checkin 8a271389

 was
technically wrong, because the implementation needlessly confusing.

The sane interface is for it to take a semiclosed range like just
about everything else (as evidenced by the sheer number of "- 1"'s
removed by that patch) so change the actual implementation to match.

Reported-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <20091119202341.GA4420@sgi.com>