mmc: sh_mmcif: 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 if needed.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20191217113031.31847-1-peter.ujfalusi@ti.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sh_mmcif.c

@@ -432,8 +432,12 @@ static void sh_mmcif_request_dma(struct sh_mmcif_host *host)
 		host->chan_rx = sh_mmcif_request_dma_pdata(host,
 							pdata->slave_id_rx);
 	} else {
-		host->chan_tx = dma_request_slave_channel(dev, "tx");
-		host->chan_rx = dma_request_slave_channel(dev, "rx");
+		host->chan_tx = dma_request_chan(dev, "tx");
+		if (IS_ERR(host->chan_tx))
+			host->chan_tx = NULL;
+		host->chan_rx = dma_request_chan(dev, "rx");
+		if (IS_ERR(host->chan_rx))
+			host->chan_rx = NULL;
 	}
 	dev_dbg(dev, "%s: got channel TX %p RX %p\n", __func__, host->chan_tx,
 		host->chan_rx);