libaudio: Fix initial glitch during headset insertion[Chaithanya Krishna Bacharaju]

-Short glitch is heard on headset when headset is plugged in
while playing ringtone from settings.
-When headset is plugged in playback switches to combo device
but immediately moves to headset for a small period. After that
it moves back to combo device causing a short glitch heard on
headset. This is because of redundant code in setForceUse.
-Remove the extra code to avoid such issues.