ASoC: soc.h: add snd_soc_card_is_instantiated() helper

ASoC framework/driver checks whether card was instantiated every
where. Then, it should check card pointer too in such case.
This patch adds snd_soc_card_is_instantiated() for it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/875ycnfoqp.wl-kuninori.morimoto.gx@renesas.com


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