staging: greybus: audio: Add helper APIs for dynamic audio modules

Greybus Codec driver allows modules to be dynamically added and removed,
which further requires updating the DAPM configurations as well.

With current snd_soc architecture, dynamic audio modules is not yet
supported. This patch provides helper APIs to update DAPM configurations
in response to modules which are dynamically added or removed. The
source is primarily based on snd_dapm.c

Signed-off-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/35e1baaae10a3f2162e71be4c2f75a701584f0e6.1594290158.git.vaibhav.sr@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>