ASoC: clock gating is decided by bool on snd_soc_of_parse_daifmt()

ASoC clock gate settings are continuous/gated only.
This patch decides it as bool, then, gated clock will be default.
Special thanks to Stephen

Cc: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>