ASoC: soc-core.c: add snd_soc_{of_}get_dlc()

ASoC: soc-core.c: add snd_soc_{of_}get_dlc()

Current soc-core.c has snd_soc_{of_}get_dai_name() to get DAI name
for dlc (snd_soc_dai_link_component). It gets .dai_name, but we need
.of_node too. Therefor user need to arrange.

It will be more useful if it gets both .dai_name and .of_node.
This patch adds snd_soc_{of_}get_dlc() for it, and existing functions
uses it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87r0q6dgnm.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>