dmaengine: mmp_tdma: Do not ignore slave config validation errors

With an invalid dma_slave_config set previously,
mmp_tdma_prep_dma_cyclic() would detect an error whilst configuring the
channel, but proceed happily on:

  [  120.756530] mmp-tdma d42a0800.adma: mmp_tdma: unknown burst size.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Link: https://lore.kernel.org/r/20200419164912.670973-2-lkundrak@v3.skSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/mmp_tdma.c

@@ -443,7 +443,8 @@ static struct dma_async_tx_descriptor *mmp_tdma_prep_dma_cyclic(
 	if (!desc)
 		goto err_out;
 
-	mmp_tdma_config_write(chan, direction, &tdmac->slave_config);
+	if (mmp_tdma_config_write(chan, direction, &tdmac->slave_config))
+		goto err_out;
 
 	while (buf < buf_len) {
 		desc = &tdmac->desc_arr[i];