ASoC: soc.h: remove snd_soc_disconnect_sync()

There is no snd_soc_disconnect_sync() implementation, and no one is
using it. Let's remove it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/87jz6qpql7.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>