dmaengine: dw-axi-dmac: Add support for CV1800B DMA

dmaengine: dw-axi-dmac: Add support for CV1800B DMA

As the DMA controller on Sophgo CV1800 series SoC only has 8 channels,
the SoC provides a dma multiplexer to reuse the DMA channel. However,
the dma multiplexer also controls the DMA interrupt multiplexer, which
means that the dma multiplexer needs to know the channel number.

Allow the driver to use DMA phandle args as the channel number, so the
DMA multiplexer can route the DMA interrupt correctly.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260120013706.436742-3-inochiama@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>