dt-bindings: iio: ad4695: fix common-mode-channel

The common-mode-channel property is a scalar, not an array, so we should
not be using items: in the schema when specifying allowable values.

Reported-by: Rob Herring <robh@kernel.org>
Closes: https://lore.kernel.org/linux-iio/CAL_JsqKaddw8FnPfdnhKhHUb8AcTxFadc_eZmxjX0QxFR80=mw@mail.gmail.com/


Fixes: b40cafc1 ("dt-bindings: iio: adc: add AD4695 and similar ADCs")
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20240808-iio-adc-ad4695-fix-dt-bindings-v1-1-5cf37b9547b0@baylibre.com


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