ASoC: rsnd: remove Gen1 support from SRC

This patch removes SRC Gen1 support which has no user on upstream.
Historically, SRC Gen1 was created as prepare for SRC Gen2 support.
It works well for Gen2 support, but Gen1 is not same as Gen2.
So now, Gen1 support is no longer needed. Thanks Gen1 and Bye-bye.

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