Update METADATA to link to upstream project am: 2e54c35cfe

Original change: https://android-review.googlesource.com/c/platform/external/libmpeg2/+/2475549

Change-Id: I649e420cd68430882358769aaae499958a65bb4b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>