dmaengine: ppc4xx_adma: convert callback to helper function

This is in preperation of moving to a callback that provides results to the
callback for the transaction. The conversion will maintain current behavior
and the driver must convert to new callback mechanism at a later time in
order to receive results.
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/ppc4xx/adma.c

@@ -1485,10 +1485,7 @@ static dma_cookie_t ppc440spe_adma_run_tx_complete_actions(
 		/* call the callback (must not sleep or submit new
 		 * operations to this channel)
 		 */
-		if (desc->async_tx.callback)
-			desc->async_tx.callback(
-				desc->async_tx.callback_param);
-
+		dmaengine_desc_get_callback_invoke(&desc->async_tx, NULL);
 		dma_descriptor_unmap(&desc->async_tx);
 	}