Fix issue 2349345: Media sound output stuck on earpiece rather than speaker.

This change fixes a problem occuring when an application (for instance a VoIP application)
changes the audio mode to MODE_IN_CALL and crashes. In this case, the audio routing policy
remains as if we were in call until the audio mode is changed back to MODE_NORMAL, for instance when a new call
made or received and terminated.

The fix consists in registering a death receipient to the binder that made the setMode() request and resetting the audio
mode in case of client process crash.