pata_it8213: fix UDMA handling

Driver should program the cycle timing not the mode number
(doing the latter results in wrong timings being used).

There shouldn't be any problems with it as IDE it8213 host driver
has been doing it this way for years.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>