regulator: cpr3: Add voltage boost support for CPR4 controllers

Voltage boost is a CPR4 hardware feature which raises the VDD supply
voltage when the number of active cores reaches a certain threshold.
It then reduces the voltage back down when the active core count
condition is no longer met. Add support to enable and configure this
feature.

Change-Id: Iccfc2ddddb6621a150235cb2c46adfd1b884dbc2
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>