ASoC: rsnd: use for_each_rsnd_mod_xxx() on rsnd_rdai_continuance_probe()

Now, we have for_each_rsnd_mod(), let's use it

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