ide-atapi: teach ide atapi about drive->waiting_for_dma

In addition, we wait for DRQ to be asserted by repeatedly polling
device status no matter what DRQ type each device implements.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>