greybus: audio: Maintain module stream state for each data connection

For SPK module, each data connection corresponds to codec DAI. Now
stream state is maintained for each DAI. So, need to maintain stream
state for each DAI/data connection for individual module as well.

Signed-off-by: Vaibhav Agarwal <vaibhav.agarwal@linaro.org>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>