releasetools: Don't delete the device specific files

They are needed for extract-files to work

Change-Id: I8d5d69c20f487708c519b2e1b8dbf8f4bfa43229
Build charger and stop using a prebuilt charge_only_mode

Change-Id: I7fe90998a5cd0312c0a031d197df92ceee28c6f4