net: mvpp2: fix possible invalid pointer dereference

It will cause invalid pointer dereference to priv->cm3_base behind,
if PTR_ERR(priv->cm3_base) in mvpp2_get_sram().

Fixes: e54ad1e0 ("net: mvpp2: add CM3 SRAM memory map")
Signed-off-by: Hui Tang <tanghui20@huawei.com>
Link: https://lore.kernel.org/r/20221117084032.101144-1-tanghui20@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c

@@ -7350,6 +7350,7 @@ static int mvpp2_get_sram(struct platform_device *pdev,
 			  struct mvpp2 *priv)
 {
 	struct resource *res;
+	void __iomem *base;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
 	if (!res) {
@@ -7360,9 +7361,12 @@ static int mvpp2_get_sram(struct platform_device *pdev,
 		return 0;
 	}
 
-	priv->cm3_base = devm_ioremap_resource(&pdev->dev, res);
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
 
-	return PTR_ERR_OR_ZERO(priv->cm3_base);
+	priv->cm3_base = base;
+	return 0;
 }
 
 static int mvpp2_probe(struct platform_device *pdev)