ASoC: amd: ps: add comments for DMA irq bits mapping

Add comments for DMA stream id and IRQ bit mapping in
ACP_EXTERNAL_CNTL & ACP_EXTERNAL_CNTL1 registers for
SDW0 and SDW1 manager instances.

Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@amd.com>
Link: https://lore.kernel.org/r/20230626105356.2580125-1-Vijendar.Mukunda@amd.com


Signed-off-by: Mark Brown <broonie@kernel.org>