regulator: max20010: Add max20010 regulator driver

The max20010 external buck supplies VDD_GFX for msm8996-auto
boards. Add max20010 regulator device driver to program the
necessary configuration as per the board specific requirements.

CRs-Fixed: 2062515
Change-Id: I68ad73e0c7cff1a87d218dc4677801f9e0206db6
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>