drivers: lmh-dcvs: Add support for two QREF regulators

Isens hardware requires the QREF regulators to be active for its
functionality. There are two QREF regulators at different supply
voltages.

Add support to use and vote for both the QREF regulators for Isens
functionality.

Change-Id: Id865d7c7df976f6802e480a7610fefbdadef544b
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>