ASoC: Introduce snd_soc_of_get_dai_link_cpus

This function is an analogue of snd_soc_of_get_dai_link_codecs to help
machine drivers read CPU DAI lists from devicetrees.

Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20220331000449.41062-5-povik+lin@cutebit.org


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