iio: move 'indio_dev->info' null check first in __iio_device_register()

Moves this to be the first check, as it's very simple and fails the
registration earlier, instead of potentially initializing the
'indio_dev->label' and checking for duplicate indexes, and then failing
with this simple-check.

This is a minor optimization, since '__iio_device_register()' will waste
fewer validation cycles in case 'indio_dev->info' is NULL.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/industrialio-core.c

@@ -1711,6 +1711,9 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
 {
 	int ret;
 
+	if (!indio_dev->info)
+		return -EINVAL;
+
 	indio_dev->driver_module = this_mod;
 	/* If the calling driver did not initialize of_node, do it here */
 	if (!indio_dev->dev.of_node && indio_dev->dev.parent)
@@ -1723,9 +1726,6 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
 	if (ret < 0)
 		return ret;
 
-	if (!indio_dev->info)
-		return -EINVAL;
-
 	/* configure elements for the chrdev */
 	indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);