ASoC: rsnd: enable rsnd_ssi_use_busif() for DMA

Renesas R-Car sound driver uses SSI, but the DMA interfaces are
SSI/SSIU. This interface is based on SSI/SRC/DVC connection.
And DMA function needs to know which interface is used somehow.
This patch enables rsnd_ssi_use_busif() for DMA.

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