[PATCH] ahci: disable NCQ support on vt8251

vt8251 chokes on NCQ commands.  Two different disks from different
vendors are showing the same symptom and it seems that the windows
driver from via doesn't support NCQ either.  Disable NCQ support on
this controller for the time being.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Aalderd Bouwman <boac@wanadoo.nl>
Cc: Bastiaan Jacques <b.jacques@planet.nl>
Signed-off-by: Jeff Garzik <jeff@garzik.org>