dt-bindings: iio: light: add VEML6040 RGBW-LS

Device tree bindings for the vishay VEML6040 RGBW light sensor iio
driver

Signed-off-by: Arthur Becker <arthur.becker@sentec.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240604-veml6040-v4-2-5a4d59597874@sentec.com


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