iio: buffer-dmaengine: Use dmaengine_terminate_sync()

The DMAengine framework gained support for synchronized transfer
termination. Use the new dmaengine_terminate_sync() function instead of
dmaengine_terminate_all(), this avoids a potential race condition when
disabling the buffer.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/buffer/industrialio-buffer-dmaengine.c

@@ -93,12 +93,7 @@ static void iio_dmaengine_buffer_abort(struct iio_dma_buffer_queue *queue)
 	struct dmaengine_buffer *dmaengine_buffer =
 		iio_buffer_to_dmaengine_buffer(&queue->buffer);
 
-	dmaengine_terminate_all(dmaengine_buffer->chan);
-	/* FIXME: There is a slight chance of a race condition here.
-	 * dmaengine_terminate_all() does not guarantee that all transfer
-	 * callbacks have finished running. Need to introduce a
-	 * dmaengine_terminate_all_sync().
-	 */
+	dmaengine_terminate_sync(dmaengine_buffer->chan);
 	iio_dma_buffer_block_list_abort(queue, &dmaengine_buffer->active);
 }