dt-bindings: iio: ad74413r: add optional reset-gpios

The ad74412 and ad74413 devices have an active-low reset pin. Add a
binding allowing one to specify a gpio tied to that.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221115095517.1008632-3-linux@rasmusvillemoes.dk


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