scsi: ufs: Add support for turning off UFS power supplies

UFS3.0 and newer devices use Vcc and Vccq(1.2V) power supplies
while UFS2.1 devices use Vcc and Vccq2(1.8V) power supplies.
If the system allows turning off these regulators during
power collapse events or system suspend events, then turn off
the regulators to save power. If the UFS device power supplies
are turned off, the UFS host will perform full initialization
sequence to the UFS device during system resume events.

Change-Id: I652702b0e72d37c76f0551688d050b88b7f13984
Signed-off-by: Bao D. Nguyen <nguyenb@codeaurora.org>