Remove 64-bit-only configs and default to 64-bit-only

Remove option for _64 and default to 64-bit only builds.
Removes the (out of date) manifest_64 files.
Removes OMX since it is not supported for 64-bits.

Bug: 213924541
Test: Build, Boot, YouTube playback, Play store, Camera
Signed-off-by: Pat Tjin <pattjin@google.com>
Change-Id: I1e97903b598a2fff46d912a009b2bc73f1b0f466
7 files changed