dmaengine: txx9dmac: 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/txx9dmac.c

@@ -403,16 +403,14 @@ static void
 txx9dmac_descriptor_complete(struct txx9dmac_chan *dc,
 			     struct txx9dmac_desc *desc)
 {
-	dma_async_tx_callback callback;
-	void *param;
+	struct dmaengine_desc_callback cb;
 	struct dma_async_tx_descriptor *txd = &desc->txd;
 
 	dev_vdbg(chan2dev(&dc->chan), "descriptor %u %p complete\n",
 		 txd->cookie, desc);
 
 	dma_cookie_complete(txd);
-	callback = txd->callback;
-	param = txd->callback_param;
+	dmaengine_desc_get_callback(txd, &cb);
 
 	txx9dmac_sync_desc_for_cpu(dc, desc);
 	list_splice_init(&desc->tx_list, &dc->free_list);
@@ -423,8 +421,7 @@ txx9dmac_descriptor_complete(struct txx9dmac_chan *dc,
 	 * The API requires that no submissions are done from a
 	 * callback, so we don't need to drop the lock here
 	 */
-	if (callback)
-		callback(param);
+	dmaengine_desc_callback_invoke(&cb, NULL);
 	dma_run_dependencies(txd);
 }