dmaengine: fsl-edma: remove 'slave_id' from fsl_edma_chan

The 'slave_id' field is redundant as it duplicates the functionality of
'srcid'. Remove 'slave_id' from fsl_edma_chan to eliminate redundancy.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20240323-8ulp_edma-v3-1-c0e981027c05@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>