ASoC: rsnd: SSI_MODE0/1 settings goes to scu.c

SRU (Gen1) / SCU (Gen2) / SSIU (Gen2) are controlled under scu.c.
(SCU + SSIU (Gen2) was SRU (Gen1))
And register of SSI_MODE0/1 are mapped on these IP.
But these have been implemented under ssi.c on this driver.
The naming is very confusable,
but it should be implemented under scu.c

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