greybus: audio: schedule workqueue to perform codec cleanup on module removal

In response to codec module removal, user space is reported about
the event. In response to this, ALSA layer will update DAPM route
and cleanup DAPM states.
As a fallback mechanism, kernel can cleanup the DAPM state for codec
module. But, this would cause immediate playback (first trial) to fail,
since DSP is still in inconsistent state.
To avoid such situation, a workqueue is scheduled for codec cleanup
with timeout=50ms.
Thus, normally it is expected from above layers to update routes and
perform cleanup. However, fallback mechanism still holds good after
50ms.

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>