ASoC: siu: don't use DMA device for channel filtering

DMA channels are filtered based on slave IDs, no need to additionally filter
on DMA device.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>