spi: at91-usart: 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>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20191113094256.1108-2-peter.ujfalusi@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-at91-usart.c

@@ -132,7 +132,7 @@ static int at91_usart_spi_configure_dma(struct spi_controller *ctlr,
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 
-	ctlr->dma_tx = dma_request_slave_channel_reason(dev, "tx");
+	ctlr->dma_tx = dma_request_chan(dev, "tx");
 	if (IS_ERR_OR_NULL(ctlr->dma_tx)) {
 		if (IS_ERR(ctlr->dma_tx)) {
 			err = PTR_ERR(ctlr->dma_tx);
@@ -145,7 +145,7 @@ static int at91_usart_spi_configure_dma(struct spi_controller *ctlr,
 		goto at91_usart_spi_error_clear;
 	}
 
-	ctlr->dma_rx = dma_request_slave_channel_reason(dev, "rx");
+	ctlr->dma_rx = dma_request_chan(dev, "rx");
 	if (IS_ERR_OR_NULL(ctlr->dma_rx)) {
 		if (IS_ERR(ctlr->dma_rx)) {
 			err = PTR_ERR(ctlr->dma_rx);