hpt366: change timing register masks

Since PIO autotuning is now done always, there's no need anymore to program
the taskfile timings also on DMA modes, so change the IDE timing register
masks accordingly, "inverting the polarity" of the masks while at it...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>