dt-bindings: iio: Drop unused header includes in examples

dt-bindings: iio: Drop unused header includes in examples

Drop includes of headers which example code does not use.  No functional
impact.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: David Heidelberg <david@ixit.cz>
Acked-by: Matti Vaittinen <mazziesaccount@gmail.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20250724111345.47889-5-krzysztof.kozlowski@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>