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: NJack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>