dt-bindings: it6505: add properties to restrict output bandwidth

dt-bindings: it6505: add properties to restrict output bandwidth

Currently there are no "upstream" users. So, no existing users to break.
Add properties to restrict dp output data-lanes and clock.

Signed-off-by: Pin-Yen Lin <treapking@chromium.org>
Signed-off-by: allen Chen <allen.chen@ite.com.tw>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221103091243.96036-2-allen.chen@ite.com.tw