audiopolicy: fix playback of multichannel pcm clips via low latency output

-Mutichannel clips, which cannot be offloaded or played via
direct output, are played using a low latency output even
if they have stream type as AUDIO_STREAM_MUSIC
-Reverting this change Ibf295f506e6ec62ffbd79091361793c18213d494
done to support multiChannel playback over HDMI as
it is supported by default.

CYNGNOS-952
CRs-Fixed: 839323
Change-Id: Iba3aa0b64fffa741704c957e07bc81b44e8a0cfe