dt-bindings: arm: rockchip: Add gru-scarlet-dumo board

Dumo is another variant of Scarlet, also known as the ASUS Chromebook
Tablet CT100. This is almost the same as Scarlet-Innolux, but uses a
specific calibration variant for the WiFi module.

Add an entry for the board compatibles.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20210812094753.2359087-2-wenst@chromium.org


Signed-off-by: Heiko Stuebner <heiko@sntech.de>