ASoC: rcar: remove rcar_gen_ops

Current rcar driver gen.c is using rcar_gen_ops
which was made with the assumption that
Gen1 and Gen2 need different behavior.
but it was not needed.
This patch removes unnecessary complex method.

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