dmaengine: add driver for Sophgo CV18XX/SG200X dmamux

Sophgo CV18XX/SG200X use DW AXI CORE with a multiplexer for remapping
its request lines. The multiplexer supports at most 8 request lines.

Add driver for Sophgo CV18XX/SG200X DMA multiplexer.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20250611081000.1187374-3-inochiama@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>