bus: fsl-mc: add back accidentally dropped error check

A previous patch accidentally dropped an error check, so add it back.

Fixes: aef85b5 ("bus: fsl-mc: MC control registers are not always available")
Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Link: https://lore.kernel.org/r/20201105153050.19662-1-laurentiu.tudor@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/bus/fsl-mc/fsl-mc-bus.c

@@ -967,8 +967,11 @@ static int fsl_mc_bus_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, mc);
 
 	plat_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-	if (plat_res)
+	if (plat_res) {
 		mc->fsl_mc_regs = devm_ioremap_resource(&pdev->dev, plat_res);
+		if (IS_ERR(mc->fsl_mc_regs))
+			return PTR_ERR(mc->fsl_mc_regs);
+	}
 
 	if (mc->fsl_mc_regs && IS_ENABLED(CONFIG_ACPI) &&
 	    !dev_of_node(&pdev->dev)) {