Revert "libstagefright: Do not offload HEVC AV decoding"

This reverts commit 1eec4467fb12ee1ae88aa9c1374c79fbf4d03e68.
Revert "AwesomePlayer: Enable audio offload for widevine"

This reverts commit 2364610daa8e076648f533f265a595474e5d5834.