dt-bindings: trivial-devices: add silabs,si7005

This simple I2C humidity sensor does not have any additional properties
and can be added to the trivial-devices binding.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231012-topic-si7005_devicetree-v1-2-6c8a6fa7b3ec@gmail.com


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