[PATCH] libata-dev: Minor fix for ata_hsm_move() to work with ata_host_intr()

Minor fix for ata_hsm_move() to work with ata_host_intr().
Changes:
- WARN_ON() and comment fix
- Make the HSM_ST_LAST device status checking more rigid.
- Treat unknown HSM state as BUG().

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