ASoC: add Renesas R-Car Generation feature

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)

The main difference between Gen1 and Gen2 are
1) register offset, 2) data path

In order to control Gen1/Gen2 by same method,
this patch adds gen.c.

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