greybus: audio: Fix incorrect codec state modification

In case module is removed dynamically with ongoing playback, during
module cleanup codec state is mistakenly modified. State should be
modified for module only. Fix this.

Fixes: 76414cb499b7 ("audio: Use single codec driver
registration")

Signed-off-by: Vaibhav Agarwal <vaibhav.agarwal@linaro.org>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Alex Elder <elder@linaro.org>