tty: serial: msm_serial: 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/20191113094618.1725-3-peter.ujfalusi@ti.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/msm_serial.c

@@ -301,7 +301,7 @@ static void msm_request_tx_dma(struct msm_port *msm_port, resource_size_t base)
 	dma = &msm_port->tx_dma;
 
 	/* allocate DMA resources, if available */
-	dma->chan = dma_request_slave_channel_reason(dev, "tx");
+	dma->chan = dma_request_chan(dev, "tx");
 	if (IS_ERR(dma->chan))
 		goto no_tx;
 
@@ -344,7 +344,7 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
 	dma = &msm_port->rx_dma;
 
 	/* allocate DMA resources, if available */
-	dma->chan = dma_request_slave_channel_reason(dev, "rx");
+	dma->chan = dma_request_chan(dev, "rx");
 	if (IS_ERR(dma->chan))
 		goto no_rx;