[1/3] AudioEffects: Add center frequency param to bassboost

Change-Id: Ia47a3f679a82392232b33b72e8dbd3b2545ee109
[2/3] audio_effects: Add a stereo widening effect

Change-Id: I0dd68fef857e8a031f52a63a81c642cb930419c6
Merge "[2/3] audio_effects: Add a stereo widening effect" into android-4.4
Merge remote-tracking branch 'omni/android-4.4' into kitkat