ASoC: rsnd: ssiu: Support BUSIF other than BUSIF0

Currently only BUSIF0 is supported by SSIU, all register setting
is done only for BUSIF.

Since BUSIF1 ~ BUSIF7 has been supported, so also support
these BUSIF from SSIU.

One note is that we can't support SSI9-4/5/6/7 so far,
because its address is out of calculation rule.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Timo Wischer <twischer@de.adit-jv.com>
[Kuninori: tidyup for upstream]
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>