iio: humditiy: hdc3020: fix units for temperature and humidity measurement

iio: humditiy: hdc3020: fix units for temperature and humidity measurement

According to the ABI the units after application of scale and offset are
milli degrees for temperature measurements and milli percent for relative
humidity measurements. Currently the resulting units are degree celsius for
temperature measurements and percent for relative humidity measurements.
Change scale factor to fix this issue.

Fixes: c9180b8e39be ("iio: humidity: Add driver for ti HDC302x humidity sensors")
Reported-by: Chris Lesiak <chris.lesiak@licorbio.com>
Suggested-by: Chris Lesiak <chris.lesiak@licorbio.com>
Reviewed-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>