ASoC: atmel_ssc_dai: Fix DMA params for different SSC

follow-up patch from c706f2e5 ASoC: atmel_ssc_dai: distinguish the
different SSC

cpu_dai id is always 0, use platform_device id to distinguish DMA
parameters of SSCs

Signed-off-by: Peter Meerwald-Stadler <p.meerwald@bct-electronic.com>
Signed-off-by: Mark Brown <broonie@kernel.org>