x86: revert "x86: CPA: avoid split of alias mappings"

Revert:

  commit 8be8f54b


  Author: Thomas Gleixner <tglx@linutronix.de>
  Date:   Sat Feb 23 20:43:21 2008 +0100

      x86: CPA: avoid split of alias mappings

because it clearly mishandles the case when __change_page_attr(), called
from __change_page_attr_set_clr(), changes cpa->processed to 1 and
cpa_process_alias(cpa) is executed right after that.

This crashes my x86-64 test box early in the boot process
(ref. http://bugzilla.kernel.org/show_bug.cgi?id=10140#c4).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>