overlay: use DEVICE_PACKAGE_OVERLAYS

This is the old behavior. It was included in a commit
that overrode vendor/cm which we don't need to do anymore.

Change-Id: I64ebb5b9e60124359f875c291429839d7c8d7282
Merge "overlay: use DEVICE_PACKAGE_OVERLAYS" into cm-11.0
Merge remote-tracking branch 'upstream/cm-11.0' into cm-11.0