x86: restore pda nodenumber field

  * Restore the nodenumber field in the x86_64 pda.  This field is slightly
    different than the x86_cpu_to_node_map mainly because it's a static
    indication of which node the cpu is on while the cpu to node map is a
    dyanamic mapping that may get reset if the cpu goes offline.  This also
    simplifies the numa_node_id() macro.

For inclusion into sched-devel/latest tree.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>