ASoC: rsnd: no exception for SCU

ASoC: rsnd: no exception for SCU

R-Car Gen1 and Gen4 doesn't have SCU, and current driver checks Gen1
(only) on each devices (A). But these drivers are assuming it might be
not enabled after that (B).

	/* This driver doesn't support Gen1 at this point */
(A)	if (rsnd_is_gen1(priv))
		return 0;

(B)	node = rsnd_src_of_node(priv);
	if (!node)
		return 0; /* not used is not error */

Gen4 DT doesn't have these device settings. (A) check doesn't work for
it, but (B) check handling it.
Gen1 DT doesn't have these device settings either, and (A) is handling
it, but (B) only is very enough. (A) is no longer needed.

This patch removes (A)

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://msgid.link/r/87v850a4dl.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>