pdc202xx_new: Enable ATAPI DMA

[ bart: the ressurection of 2 years old patch which slipped thru the cracks
  (thanks to Sergei Shtylyov for finding it) ]

These is the patch to turn on pdc202xx_new for ATAPI DMA.  When testing, it
works fine without the (request_bufflen % 256) workaround as needed in libata.
ide-scsi filters out (pc->request_transfer % 1024) and use PIO, so the pdc202xx
ATAPI DMA problem is avoid.  Both ide-cd and ide-scsi won't hit the ATAPI DMA
problem on pdc202xx_new.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>