ASoC: rsnd: tidyup rsnd_dma_ops definition place

rsnd_dma_ops is used only from dma.c, rsnd.h doesn't need it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>