greybus: audio: Added jack support to audio module

Register jack with ASoC sound card in case audio module
populates it via codec FW. Currently, only a single jack
with 4 buttons can be registered for each module.

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>