dmaengine: at_hdmac: Remove superfluous cast

Conversions of void * are applied automatically when other pointer types
are assigned to and from void *. Remove the superfluous cast.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com
Link: https://lore.kernel.org/r/20221025090306.297886-19-tudor.ambarus@microchip.com


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