audio: Avoid mute delay during stopping of tones.

 - Each time tone is played extra delay added due to
   checkDeviceMuteStrategies during stop of tone.
 - Such mute delay is not needed in this scenario when
   there is no actual device switch.
 - Fix is to avoid mute during stop of tone.

Change-Id: I16e11ab846044fc14cb625cee8bf8273e0e4bcc3