dma: ste_dma40: Convert to PM macros while providing the PM callbacks

Converting to the PM macros makes us simplify and remove some code.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>