ASoC: msm: Add 8-channel L-PCM TX support

There is use case that the HDMI input goes through MI2S TX
interface to ADSP. Add 8-channel L-PCM TX support for this
use case.

Change-Id: Iaf10ec357a25fe4cf80e36a2ceba3d113e9b0416
Signed-off-by: Subhash Chandra Bose Naripeddy <snariped@codeaurora.org>