[PATCH] x86-64: Don't trust boot_cpu_id in the mptable.

It could be wrong for kexec or other cases. Read it from
the CPU instead.

Signed-off-by: Murali <muralim@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>