greybus: audio: Use CSD instead of E2EFC for audio data connections

There is no reason to use end-to-end flow control for Greybus
audio data connections so disable it and enable Controlled
Segment Dropping (CSD).

Testing Done: Played music using audio modules on an EVT1.5.

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