healthd: Read the max power supply voltage

With Type-C PD, VBUS can no longer be assumed to
to be at 5V. Read the "voltage_max" field from the
power_supply class node and export it through
BatteryProperties service.

Bug: 25229483
Change-Id: I04e32d9783a21bab375f1724758a9eeace2a047c
(cherry picked from commit 42d9133a231f05f426ca0971c281ffd387e34d01)
1 file changed