ASoC: rcar: off by one in rsnd_scu_set_route()

If "id == ARRAY_SIZE(routes)" then we read one space beyond the end of
the routes[] array.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>