dt-bindings: phy: rockchip-inno-dsidphy: Document rv1126

Document a compatible string for the rv1126 dsi-dphy.

Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230731110012.2913742-4-jagan@edgeble.ai
Signed-off-by: Vinod Koul <vkoul@kernel.org>