dt-bindings: iio: st,st-sensors add LPS22DF.

Add support for the ST LPS22DF, an I2C/SPI pressure sensor.

Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220909161611.780720-1-martyn.welch@collabora.co.uk


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