net: korina: Fix return value check in korina_probe()

In case of error, the function devm_platform_ioremap_resource_byname()
returns ERR_PTR() and never returns NULL. The NULL test in the return
value check should be replaced with IS_ERR().

Fixes: b4cd249a ("net: korina: Use devres functions")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/korina.c

@@ -1315,23 +1315,23 @@ static int korina_probe(struct platform_device *pdev)
 	lp->tx_irq = platform_get_irq_byname(pdev, "tx");
 
 	p = devm_platform_ioremap_resource_byname(pdev, "emac");
-	if (!p) {
+	if (IS_ERR(p)) {
 		printk(KERN_ERR DRV_NAME ": cannot remap registers\n");
-		return -ENOMEM;
+		return PTR_ERR(p);
 	}
 	lp->eth_regs = p;
 
 	p = devm_platform_ioremap_resource_byname(pdev, "dma_rx");
-	if (!p) {
+	if (IS_ERR(p)) {
 		printk(KERN_ERR DRV_NAME ": cannot remap Rx DMA registers\n");
-		return -ENOMEM;
+		return PTR_ERR(p);
 	}
 	lp->rx_dma_regs = p;
 
 	p = devm_platform_ioremap_resource_byname(pdev, "dma_tx");
-	if (!p) {
+	if (IS_ERR(p)) {
 		printk(KERN_ERR DRV_NAME ": cannot remap Tx DMA registers\n");
-		return -ENOMEM;
+		return PTR_ERR(p);
 	}
 	lp->tx_dma_regs = p;