dmaengine: altera-msgdma: Correctly handle descriptor callbacks

DMA clients can provide one of two types of callbacks. For this reason
dmaengine drivers should not directly invoke `callback`, but always use
dmaengine_desc_callback_invoke(). This makes sure that both types of
callbacks are handled correctly.

The altera-msgdma driver currently doesn't do this and only handles the
`callback` type callback. If the client used the `callback_result` type
callback it will not be called.

Fix this by switching to `dmaengine_desc_callback_valid()` and
`dmaengine_desc_callback_invoke()`.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/altera-msgdma.c

···
 	struct msgdma_sw_desc *desc, *next;
 
 	list_for_each_entry_safe(desc, next, &mdev->done_list, node) {
-		dma_async_tx_callback callback;
-		void *callback_param;
+		struct dmaengine_desc_callback cb;
 
 		list_del(&desc->node);
 
-		callback = desc->async_tx.callback;
-		callback_param = desc->async_tx.callback_param;
-		if (callback) {
+		dmaengine_desc_get_callback(&desc->async_tx, &cb);
+		if (dmaengine_desc_callback_valid(&cb)) {
 			spin_unlock(&mdev->lock);
-			callback(callback_param);
+			dmaengine_desc_callback_invoke(&cb, NULL);
 			spin_lock(&mdev->lock);
 		}