staging: greybus: audio: Resolve compilation errors for GB codec module

Due to dependencies on ASoC framework changes, GB dummy codec module
compilation is currently disabled. This patch updates codec driver as
per the latest ASoC APIs.

Signed-off-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/dd66a960fca186da055600fe1e622b7a814cb543.1594290158.git.vaibhav.sr@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>