mm-video: vdec: Allow devices to disable adaptive playback

* Older Adreno drivers have problems with adaptive playback due to
  incompatibility inside the library.
* Allow devices to choose to not advertise adaptive playback capability
  if bad output results.

Change-Id: Ie68fb9f8ec2122f2fc6e6654d9fdbc773dff509a
media: Avoid collision with FFMPEG plugin

Change-Id: Ica2cdf9f6572ec18f396d25758cbb2be1359ac0b