GEODE: reboot fixup for geode machines with CS5536 boards

Writing to MSR 0x51400017 forces a hard reset on CS5536-based machines,
this has the reboot fixup do just that if such a board is detected.

Acked-by: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>