defconfig: msm9625: Enable power supply class

Power supply APIs are required by USB driver for USB charging.
This change will not add an actual battery charger, but only
the power supply class and its APIs.

Change-Id: Icd50edf2dbee3127c935d354bd107d8f162b3cb3
Signed-off-by: Jack Pham <jackp@codeaurora.org>