[PATCH] libata-dev: Fix merge problem with upstream

Fix merge problem with upstream.
Changes:
1. add missing dev->cdb_len = 16 for ATA devices
2. use ata_pio_task instead of atapi_packet_task

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>