tty: serial: tegra: Use dma_request_chan() directly for channel request

dma_request_slave_channel_reason() is:
#define dma_request_slave_channel_reason(dev, name) \
	dma_request_chan(dev, name)
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20191113094618.1725-4-peter.ujfalusi@ti.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/serial-tegra.c

@@ -1122,8 +1122,7 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
 	int ret;
 	struct dma_slave_config dma_sconfig;
 
-	dma_chan = dma_request_slave_channel_reason(tup->uport.dev,
-						dma_to_memory ? "rx" : "tx");
+	dma_chan = dma_request_chan(tup->uport.dev, dma_to_memory ? "rx" : "tx");
 	if (IS_ERR(dma_chan)) {
 		ret = PTR_ERR(dma_chan);
 		dev_err(tup->uport.dev,