Renesas R-Car series sound circuit consists of SSI and its peripheral.
But this peripheral circuit is different between
R-Car Generation1 (E1/M1/H1) and Generation2 (E2/M2/H2)
(Actually, there are many difference in Generation1 chips)

Gen1 series consists of SRU/SSI/ADG, and
Gen2 series consists of SCU/SSIU/SSI/ADG.

In order to control these by same method,
these are treated as "mod" on this driver.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>