scsi: ufs: fix ufs error on shoutdown

When running with a UFS controller but without a UFS device,
there are errors on shoutdown. This is because the device
state variable was not initialized before shutdown.
To solve it the device state is initialized to power off.

Change-Id: I89a9def0ed399907896d1492b7f592fc928be260
Signed-off-by: Dolev Raviv <draviv@codeaurora.org>