x86, platform: Change is_untracked_pat_range() to bool; cleanup init

- Change is_untracked_pat_range() to return bool.
- Clean up the initialization of is_untracked_pat_range() -- by default,
  we simply point it at is_ISA_range() directly.
- Move is_untracked_pat_range to the end of struct x86_platform, since
  it is the newest field.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20091119202341.GA4420@sgi.com>