healthd: Add support for HVDCP_3 chargers

HVDCP_3 is a high voltage DCP charger where the charger's voltage
can be changed by issuing pulses on the D+/D- lines. Add support to
recognize it and treat it as an AC power source.

Change-Id: Ib719529904e8b7a676bbdc5f5953f0f9da6df3fa