dmaengine: fsl_raid: 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/fsl_raid.c

@@ -134,16 +134,8 @@ static void fsl_re_issue_pending(struct dma_chan *chan)
 
 static void fsl_re_desc_done(struct fsl_re_desc *desc)
 {
-	dma_async_tx_callback callback;
-	void *callback_param;
-
 	dma_cookie_complete(&desc->async_tx);
-
-	callback = desc->async_tx.callback;
-	callback_param = desc->async_tx.callback_param;
-	if (callback)
-		callback(callback_param);
-
+	dmaengine_desc_get_callback_invoke(&desc->async_tx, NULL);
 	dma_descriptor_unmap(&desc->async_tx);
 }