iio: adc: men_z188_adc: Fix a resource leak in an error handling path

If iio_device_register() fails, a previous ioremap() is left unbalanced.

Update the error handling path and add the missing iounmap() call, as
already done in the remove function.

Fixes: 74aeac4d ("iio: adc: Add MEN 16z188 ADC driver")
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/320fc777863880247c2aff4a9d1a54ba69abf080.1643445149.git.christophe.jaillet@wanadoo.fr
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/men_z188_adc.c

@@ -103,6 +103,7 @@ static int men_z188_probe(struct mcb_device *dev,
 	struct z188_adc *adc;
 	struct iio_dev *indio_dev;
 	struct resource *mem;
+	int ret;
 
 	indio_dev = devm_iio_device_alloc(&dev->dev, sizeof(struct z188_adc));
 	if (!indio_dev)
@@ -128,8 +129,14 @@ static int men_z188_probe(struct mcb_device *dev,
 	adc->mem = mem;
 	mcb_set_drvdata(dev, indio_dev);
 
-	return iio_device_register(indio_dev);
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto err_unmap;
+
+	return 0;
 
+err_unmap:
+	iounmap(adc->base);
 err:
 	mcb_release_mem(mem);
 	return -ENXIO;