pdc_adma use libata-core PIO path but were left out
during ->data_xfer conversion.  Initialize with proper callbacks.

This patch is against the current libata-dev#ALL.  Controllers which
implement their own PIO HSM (ahci and sil24) don't need ->data_xfer, so the
above two are the only drivers which were left out during conversion.

From: "Barry K. Nathan" <barryn@pobox.com>
Signed-off-by: Barry K. Nathan <barryn@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>