ASoC: msmcobalt: add channel configuration for proxy port

Add channel configuration support and hardware params
configuration for proxy audio back end so that clients
can configure channel dynamically.

Change-Id: I1200aecb864c460f8096774ced62f37a023e378e
Signed-off-by: Shiv Maliyappanahalli <smaliyap@codeaurora.org>