dt-bindings: w1: UART 1-Wire bus

Add device tree binding for UART 1-Wire bus.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
Link: https://lore.kernel.org/r/20240209-w1-uart-v6-2-3e753c149196@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>