ASoC: add soc-card.c

Current ALSA SoC has some snd_soc_card_xxx() functions,
and card->xxx() callbacks.
But, it is implemented randomly at random place.

To collect all card related functions into one place,
this patch creats new soc-card.c.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/87blm825kt.wl-kuninori.morimoto.gx@renesas.com


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