ASoC: samsung: s3c24xx-i2s: Don't use platform_data for DMA parameters

Since the s3c24xx-dma is converted to use DMA map we can rely on the
DMA subsystem to match DMA channels and slave devices, rather than
passing DMA details from platform_data.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>