regulator: cpr3-regulator: add support for voltage adjustment specification

Add support in the cpr3-regulator driver to handle open-loop
voltage and closed-loop voltage adjustments which are specified
in CPR3 thread device tree nodes.  These adjustments can be used
to add or remove voltage margin per-fuse-corner or per-corner.
This ensures stability while also reducing power consumption.

Change-Id: I7248819a282dfaaff672049535f491ee77784de3
Signed-off-by: David Collins <collinsd@codeaurora.org>