My laptop (Acer Travelmate 660) always cuts the power when rebooting
which causes the disk to emergency-park it's head.

Add a dmi check to stop disk as for shutdown on this laptop.
Signed-off-by: NBruno Prémont <bonbons@linux-vserver.org>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>