scsi: ufs: add voting support for host controller power

Add the support for voting of the regulator powering the
host controller logic.

Change-Id: Ibcb7eb4bcc6fabd49aea48957028a21a373c833b
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Raviv Shvili <rshvili@codeaurora.org>