staging: greybus: audio: Ensure proper byte order

Proper byte order was completely disregarded for multi byte data shared
between AP and module (and APB1). Fix this.

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