dmaengine: at_xdmac: use pm_ptr()

Use pm_ptr() macro to fill at_xdmac_driver.driver.pm.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20211007111230.2331837-5-claudiu.beznea@microchip.com


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