net: axienet: Fix devm_ioremap_resource return value check

Value returned by devm_ioremap_resource() was checked for non-NULL but
devm_ioremap_resource() returns IOMEM_ERR_PTR, not NULL. In case of
error this could lead to dereference of ERR_PTR.
Signed-off-by: NKrzysztof Kozlowski <k.kozlowski.k@gmail.com>
Cc: <stable@vger.kernel.org>
Fixes: 46aa27df ("net: axienet: Use devm_* calls")
Reviewed-by: NSören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1530,9 +1530,9 @@ static int axienet_probe(struct platform_device *pdev)
 	/* Map device registers */
 	ethres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	lp->regs = devm_ioremap_resource(&pdev->dev, ethres);
-	if (!lp->regs) {
+	if (IS_ERR(lp->regs)) {
 		dev_err(&pdev->dev, "could not map Axi Ethernet regs.\n");
-		ret = -ENOMEM;
+		ret = PTR_ERR(lp->regs);
 		goto free_netdev;
 	}
 
@@ -1599,9 +1599,9 @@ static int axienet_probe(struct platform_device *pdev)
 		goto free_netdev;
 	}
 	lp->dma_regs = devm_ioremap_resource(&pdev->dev, &dmares);
-	if (!lp->dma_regs) {
+	if (IS_ERR(lp->dma_regs)) {
 		dev_err(&pdev->dev, "could not map DMA regs\n");
-		ret = -ENOMEM;
+		ret = PTR_ERR(lp->dma_regs);
 		goto free_netdev;
 	}
 	lp->rx_irq = irq_of_parse_and_map(np, 1);