dmaengine: ste_dma40: Remove platform data

The Ux500 is device tree-only since ages. Delete the
platform data header and push it into or next to the driver
instead.

Drop the non-DT probe path since this will not happen.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230417-ux500-dma40-cleanup-v3-4-60bfa6785968@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>