defconfig: sdm670: enable refgen regulator driver

Enable the REFGEN regulator driver for SDM670 so that consumers
can vote on their hardware needs.

CRs-Fixed: 2113021
Change-Id: I371d59c505d7cbc2770aa10e144063569fa925fc
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>
2 files changed