ide: DMA_PIO_RETRY -> IDE_DFLAG_DMA_PIO_RETRY

Add IDE_DFLAG_DMA_PIO_RETRY and use it instead of
ide_drive_t.state + DMA_PIO_RETRY.

There should be no functional changes cause by this patch.

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