dmaengine: ste_dma40: Pass dev to OF function

The OF platform data population function only wants to
use struct device *dev, so pass that instead.

This change makes the compiler realize that the local
platform data variable is unused, so drop that too.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230417-ux500-dma40-cleanup-v3-5-60bfa6785968@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>