ASoC: msm: qdsp6v2: support for configurable bit format for AFE encoder

Add support for configurable bit width for AFE encoder.
Add new mixer ctl to set for usecases which enables
configuring different input/output bit format
on AFE for usecases such as APTXHD encoder for 24bit input
and 16bit output.

Change-Id: I62326a097cbd71a3ec2b93a0120284d8f71f5d57
Signed-off-by: Naresh Tanniru <ntanniru@codeaurora.org>