mtd: sh_flctl: use dmaengine_terminate_all() API

The drivers should use dmaengine_terminate_all() API instead of
accessing the device_control which will be deprecated soon

Acked-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>