Boeffla-Sound: Engine 1.4.8

- finally completely neutralize mic_mode to avoid any interference to related registers
  when not used (further fix for call issues with certain firmwares)
Revert "Add charge level interface (default are stock values)"

This reverts commit 21c256173bcb428ccbbccba1259f02d6b0a87aa6.
Add charge level interface

- defaults are stock currents
- now separate interfaces for ac and usb
Boeffla ramfs: Change charging level configuration according to new sys interface