Let ata_hsm_move() work with both irq-pio and polling pio codepath.

Changes:
- add a new parameter "in_wq" for polling pio
- add return value "poll_next" to tell polling pio task whether the HSM is finished
- merge code from ata_pio_first_block() to the HSM_ST_FIRST state.
- call ata_poll_qc_complete() if called from the workqueue
Signed-off-by: NAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>