m4: 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.

Change-Id: I20c3d5b44e6ed7bc71a36c6a40d0de6e65e204f3
Merge remote-tracking branch 'cm/cm-11.0' into HEAD