healthd: Don't take device-scoped battery as the main system battery.

Some devices expose the battery state of stylus etc in sysfs,
in addition to the whole system's main battery. Android only
recognizes the first battery enumerated here. We need to
filter out such HID-specific battery to let Android correctly
monitor the main battery status.

Bug: 136111013
Test: CtsBatterySavingTestCases on arcada
Change-Id: I4cbf6e3bf883fb3d107bedd2849d8ad525538629