ASoC: audio-graph: remove unused "node" from graph_parse_mclk_fs()

graph_parse_mclk_fs() has "node", but is not used.
This patch removes unused "node"

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87tuo33ubl.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>