iio: light: cm32181: Fix integartion time typo

Fix integartion time typo and while at it improve the comment with
the typo a bit in general.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>