ASoC: add snd_soc_disconnect_sync()

Now, we have snd_card_disconnect_sync() on ALSA framework.
snd_soc_disconnect_sync() is ASoC version of it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>