dmaengine: ste_dma40: Add dev helper variable

The &pdev->dev device pointer is used so many times in the
probe() and d40_hw_detect_init() functions that a local *dev
variable makes the code way easier to read.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230417-ux500-dma40-cleanup-v3-3-60bfa6785968@linaro.org


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