ASoC: simple-scu-card: tidyup codec daifmt handling method

Current simple-scu-card is handling codec daifmt by using
for_each_child_of_node(), and low-level method.
Let's use of_get_child_by_name() instead it

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