dt-bindings: iio: adc: mcp3911: add microchip,data-ready-hiz entry

The Data Ready Output Pin is either hard wired to work as high
impedance or push-pull. Make it configurable.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220815061625.35568-8-marcus.folkesson@gmail.com


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