[PATCH] libata-dev: Cleanup unused enums/functions

Cleanup the following unused functions:
- ata_pio_poll()
- ata_pio_complete()
- ata_pio_first_block()
- ata_pio_block()
- ata_pio_error()
ap->pio_task_timeout and other enums.

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