Use TARGET_UNIFIED_DEVICE to override certain ro. properties
originaly by @dhacker29
https://github.com/TEAM-Gummy/android_build/commit/3482ca7fc6d872a43f8d1cd9cad26c87a6c9dd89

with TARGET_VENDOR_INIT_LIB this will allow other uses of vendor
init lib to be defined.

Also fix evaluating the boolean properly in ota_from_target_files

Change-Id: I83041796a4ac832a43820d22a7ac36e5445c375d
Signed-off-by: cj360 <ayunker551@gmail.com>