mfd: mt6397: Do not call irq_domain_remove if PMIC unsupported

If the PMIC ID is unknown, the current code would call
irq_domain_remove and panic, as pmic->irq_domain is only
initialized by mt6397_irq_init.

Return immediately with an error, if the chip ID is unsupported.
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/mt6397-core.c

@@ -329,8 +329,7 @@ static int mt6397_probe(struct platform_device *pdev)
 
 	default:
 		dev_err(&pdev->dev, "unsupported chip: %d\n", id);
-		ret = -ENODEV;
-		break;
+		return -ENODEV;
 	}
 
 	if (ret) {