Revert "venc: Set max supported AVC level to OMX_VIDEO_AVCLevel42 on 8916"

- Venus supports decoding at 50Mbps, but only supports encoding at
  20 Mbps.

This reverts commit 42981ed07368d839aa1b87efa2f505fee19f7580.

Change-Id: I1b0f8cadc241f36ba7101748c5dbc12b22e22a10