init: add a new charger-fs trigger in the power off charging mode

Add the charger-fs trigger and mount the charger file system earlier
than the propery service init in the power off charging mode.

Change-Id: Iecc0fcdabca836365d6822ca6ef9e0944258d687
Merge pull request #13 from CarbonDev/kk

init: add a new charger-fs trigger in the power off charging mode