dmaengine: ste_dma40: Return error codes properly

This makes the probe() and its subfunction d40_hw_detect_init()
return proper error codes.

One effect of this is that deferred probe, e.g from the clock,
will start to work, would it happen. Also it is better design.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230417-ux500-dma40-cleanup-v3-7-60bfa6785968@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>