dmaengine: mmp_tdma: add missed of_dma_controller_free

The driver calls of_dma_controller_register in probe but does not free
it in remove.
Add the call to fix it.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Link: https://lore.kernel.org/r/20191115083100.12220-1-hslester96@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/mmp_tdma.c

@@ -544,6 +544,9 @@ static void mmp_tdma_issue_pending(struct dma_chan *chan)
 
 static int mmp_tdma_remove(struct platform_device *pdev)
 {
+	if (pdev->dev.of_node)
+		of_dma_controller_free(pdev->dev.of_node);
+
 	return 0;
 }