net: ll_temac: Use devm_platform_ioremap_resource_byname()

platform_get_resource() may fail and return NULL, so we had better
check its return value to avoid a NULL pointer dereference a bit later
in the code. Fix it to use devm_platform_ioremap_resource_byname()
instead of calling platform_get_resource_byname() and devm_ioremap().

Fixes: 8425c41d1ef7 ("net: ll_temac: Extend support to non-device-tree platforms")
Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: Wang Hai <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/xilinx/ll_temac_main.c

···
 	}
 
 	/* map device registers */
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	lp->regs = devm_ioremap(&pdev->dev, res->start,
-					resource_size(res));
-	if (!lp->regs) {
+	lp->regs = devm_platform_ioremap_resource_byname(pdev, 0);
+	if (IS_ERR(lp->regs)) {
 		dev_err(&pdev->dev, "could not map TEMAC registers\n");
 		return -ENOMEM;
 	}