[SCSI] pm80xx: Fix for direct attached device.

In case of direct attached SATA device delay is not enough.
It will give crash for set device state command response and
wait_for_completion is the best solution for this.

Signed-off-by:  <Nikith.Ganigarakoppal@pmcs.com>
Signed-off-by:  <Anandkumar.Santhanam@pmcs.com>
Reviewed-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>