dt-bindings: display: rockchip: convert rockchip-lvds.txt to YAML

Convert rockchip-lvds.txt to YAML.

Changed:
  Add power-domains property.
  Requirements between PX30 and RK3288

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/67771143-fd83-383d-41b2-68e8707134e8@gmail.com