defconfig: msm: Enable PMIC5 ADC for SDM855

ADC is used by clients to read voltage phone power,
on board system thermistors and PMIC GPIO signals
routed for ADC measurements.

Change-Id: Icb87a6fe1c224b24f6b4c3cafc3888c7db008b17
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>