regulator: rpm-smd-regulator: Add snapshot of rpm-smd-regulator driver

This is snapshot of the rpm-smd-regulator driver as of msm-4.14
'commit f6af62b0fbea1d0 ("regulator: rpm-smd: Send the logical mode
instead of the raw mode")'.

Change-Id: Ie7a75bc63ae2380cf22b02e6f14b1cc498feb8a5
Signed-off-by: Kavya Nunna <knunna@codeaurora.org>