ASoC: soc-core: snd_soc_get_dai_name() become non static

snd_soc_get_dai_name() is used from snd_soc_of_get_dai_name(),
and it is assuming that DT is using "sound-dai" / "#sound-dai-cells".
But graph base DT is using "remote-endpoint". This patch makes
snd_soc_get_dai_name() non static for graph support.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>