net: axienet: Mark eth_irq as optional

According to the DT binding, the Ethernet core interrupt is optional.

Use platform_get_irq_optional() to avoid the error message when the
IRQ is not specified.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1851,7 +1851,7 @@ static int axienet_probe(struct platform_device *pdev)
 		lp->rx_irq = irq_of_parse_and_map(np, 1);
 		lp->tx_irq = irq_of_parse_and_map(np, 0);
 		of_node_put(np);
-		lp->eth_irq = platform_get_irq(pdev, 0);
+		lp->eth_irq = platform_get_irq_optional(pdev, 0);
 	} else {
 		/* Check for these resources directly on the Ethernet node. */
 		struct resource *res = platform_get_resource(pdev,
@@ -1859,7 +1859,7 @@ static int axienet_probe(struct platform_device *pdev)
 		lp->dma_regs = devm_ioremap_resource(&pdev->dev, res);
 		lp->rx_irq = platform_get_irq(pdev, 1);
 		lp->tx_irq = platform_get_irq(pdev, 0);
-		lp->eth_irq = platform_get_irq(pdev, 2);
+		lp->eth_irq = platform_get_irq_optional(pdev, 2);
 	}
 	if (IS_ERR(lp->dma_regs)) {
 		dev_err(&pdev->dev, "could not map DMA regs\n");