ASoC: soc-core: enable "dai-format" on snd_soc_of_parse_daifmt()

Current snd_soc_of_parse_daifmt() detects [prefix]format, but
"format" was unclear in some case. This patch checks "dai-format"
first, and try to check "[prefix]format" if "dai-format" was not
exist.

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