iio: pressure: st_pressure: Add support for LPS22DF

Add support for ST LPS22DF pressure sensor.

Datasheet: https://www.st.com/resource/en/datasheet/lps22df.pdf


Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Link: https://lore.kernel.org/r/20220909161611.780720-2-martyn.welch@collabora.co.uk


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