mmc: pxamci: Use dma_request_chan() instead dma_request_slave_channel()

dma_request_slave_channel() is a wrapper on top of dma_request_chan()
eating up the error code.

By using dma_request_chan() directly the driver can support deferred
probing against DMA.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20191217113004.31688-1-peter.ujfalusi@ti.comSigned-off-by: NUlf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/pxamci.c

@@ -710,17 +710,19 @@ static int pxamci_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, mmc);
 
-	host->dma_chan_rx = dma_request_slave_channel(dev, "rx");
-	if (host->dma_chan_rx == NULL) {
+	host->dma_chan_rx = dma_request_chan(dev, "rx");
+	if (IS_ERR(host->dma_chan_rx)) {
 		dev_err(dev, "unable to request rx dma channel\n");
-		ret = -ENODEV;
+		ret = PTR_ERR(host->dma_chan_rx);
+		host->dma_chan_rx = NULL;
 		goto out;
 	}
 
-	host->dma_chan_tx = dma_request_slave_channel(dev, "tx");
-	if (host->dma_chan_tx == NULL) {
+	host->dma_chan_tx = dma_request_chan(dev, "tx");
+	if (IS_ERR(host->dma_chan_tx)) {
 		dev_err(dev, "unable to request tx dma channel\n");
-		ret = -ENODEV;
+		ret = PTR_ERR(host->dma_chan_tx);
+		host->dma_chan_tx = NULL;
 		goto out;
 	}