phy: Sparx5 Eth SerDes: check return value after calling platform_get_resource()

It will cause null-ptr-deref if platform_get_resource() returns NULL,
we need check the return value.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210603051014.2674744-1-yangyingliang@huawei.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/microchip/sparx5_serdes.c

@@ -2470,6 +2470,10 @@ static int sparx5_serdes_probe(struct platform_device *pdev)
 	priv->coreclock = clock;
 
 	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!iores) {
+		dev_err(priv->dev, "Invalid resource\n");
+		return -EINVAL;
+	}
 	iomem = devm_ioremap(priv->dev, iores->start, resource_size(iores));
 	if (IS_ERR(iomem)) {
 		dev_err(priv->dev, "Unable to get serdes registers: %s\n",