dt-bindings: iio: ti,tmp117: add optional label property

Add the support to provide an optional label like we do for ADC
channels to identify the device more easily.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240226121234.545662-1-m.felsch@pengutronix.de


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