ASoC: audio-graph-card: tidyup mclk-fs method

Current audio-graph-card is handling "mclk-fs" by many way.
But, it is not useful and readable.
We want to do is that allow having mclk-fs everywere.
This patch support it.
It will be overwrote if lower node has it.

sound {
	mclk-fs = <xxx>; // initial
};

codec {
	ports {
		mclk-fs = <xxx>; // overwrite
		port {
			mclk-fs = <xxx>; // overwrite
			endpoint {
				mclk-fs = <xxx>; // overwrite
			};
		};
	};
};

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