because we need it for DarwinnDelegate to forcelly disable the cache coherency feature for debugging purpose. This sys prop should be readable by all Darwinn Delegate clients, but only modifiable by `adb root`.
Test: Verified that both camera app and camera HAL can read the flag. See pending CL cl/507001854 and android_flag_permission_test.md
Bug: 262420821
Change-Id: I0ae7e02f1d4805956a05afeb92f892cbac6d5213
Previously supported in some cases. Now extend it to all common cases
Bug: 263394888
Test: Built and ran DBA Hal on Android Device
Change-Id: I9a5c6a6c8d8b6c23a7d86678ecae57a9f0bcdf7a