healthd: charger: Run animation even if capacity is 0

If charger is connected and battery capacity is 0, charging animation should
run. The device would be booted up even if capacity is 0 in off-mode charging.
At that time, it would take some time to be 1 from 0 for capacity if you
use USB charger.

Bug: 17606689
Change-Id: I37e0f1b6ab0ee1f6d833882e169bf3ea06cf2399