m8: utilize recovery_root_private

Prebuilt modules can be placed in the correct directory structure under
recovery/root and the build system will automatically copy them to the
recovery ramdisk.

* Remove charger since it is not used

Change-Id: I41818d2faf8aaafb0b8becae1ba643b79dd797e6
(cherry picked from commit 57e042183d1ec8606ae38696b3aea40a2755b8b5)