phy: ufs: put regulator to LPM mode

If regulator is marked as always on then we should atleast put
it in LPM mode as we can't disabled it.

Change-Id: I1c2f398d4a3b62d9e641ae53b7c4806b69c4862b
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Nitin Rawat <nitirawa@codeaurora.org>