ASoC: rsnd: cmd: Add missing newline to debug message

To comply with the style of all kernel messages, add newline
to the end of every message.

Fixes: 70fb1052

 ("ASoC: rsnd: add MIX (Mixer) support")
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>