dmaengine: Remove the need to declare device_control

In order to migrate the drivers without triggering a BUG_ON for the converted
drivers, which would cause bisectability issues, we need to remove that check
before removing the device_control function entirely.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>