ASoC: rsnd: enable DVC when capture

Current DVC can be enabled only when playback,
but, this came from misunderstanding.
It is not correct.

DVC <-> DMA relationship is...

Playback: MEM -> DMAC  -> SRC -> DVC -> DMACp -> SSI
Capture:  SSI -> DMACp -> SRC -> DVC -> DMAC  -> MEM

DVC can be used for both Playback/Capture

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