[PATCH] x86_64: Clean up and tweak ACPI blacklist year code

 - Move the core parser into dmi_scan.c.  It can be useful for other
   subsystems too.
 - Differentiate between field doesn't exist and field is 0 or
   unparseable.  The first case is likely an old BIOS with broken ACPI,
   the later is likely a slightly buggy BIOS where someone forget to
   edit the date.  Don't blacklist in the later case.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>