iio: potentiometer: ad5272: Correct polarity of reset

The driver should assert reset by setting the gpio high, and
then release it by setting it the gpio low. This allows the
device tree (or other hardware definition) to specify how the
gpio is configured.

For example as open drain or push-pull depending on the
connected hardware.

Signed-off-by: Phil Reid <preid@electromag.com.au>
Link: https://lore.kernel.org/r/20201124050014.4453-1-preid@electromag.com.au


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>