libaudio: enable stereowide in audio_effects.conf

this fixes the FC of DSP Manager when stereo widening is enabled

Change-Id: I72102a8cef60624482bd02ad669a881dfd3b029f
Signed-off-by: stimpz0r <stimpz0r@kritical.co>
Merge "libaudio: enable stereowide in audio_effects.conf" into android-4.4