ASoC: rsnd: extracts Gen1/Gen2 common parts

Renesas sound IP Gen1/Gen2 are similar, but different.
This patch extracts Gen1/Gen2 common and dependency parts,
and create Gen1/Gen2 ops to control it.

According to this structure, SSIU setup which
has been implemented on ssi.c can be moved to scu.c
(SRU/SSIU/SCU should be implemented on scu.c)

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

sound/soc/sh/rcar/rsnd.h

@@ -48,7 +48,7 @@ enum rsnd_reg {
 	RSND_REG_SRC_IFSCR,
 	RSND_REG_SRC_IFSVR,
 	RSND_REG_SRC_SRCCR,
-	RSND_REG_SRC_MNFSR,
+	RSND_REG_SRC_MNFSR,		/* for Gen1 */
 
 	/* ADG */
 	RSND_REG_BRRA,