Add ability to play audio to Boot Animation

Just add an audio file named audio.mp3 to system/media to play during the bootanimation

Credit to Team Bamf

Change-Id: I94ef8020870578f7d6f255467076f778467dccbd
Not needed
It's a part of this commit https://github.com/SlimRoms/frameworks_base/commit/93ae2d6b613ca98b32bb36609df49ef3df0cdc00