iio: humidity: hdc100x: fix IIO_HUMIDITYRELATIVE channel reporting

The IIO_HUMIDITYRELATIVE channel was being incorrectly reported back
as percent when it should have been milli percent. This is via an
incorrect scale value being returned to userspace.

Signed-off-by: Chris Lesiak <chris.lesiak@licor.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>