dt-bindings: display: panel: Add Raydium RM69380

Raydium RM69380 is a display driver IC used to drive OLED DSI panels.
Add a dt-binding for it.

Signed-off-by: David Wronek <david@mainlining.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240417-raydium-rm69380-driver-v4-1-e9c2337d0049@mainlining.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240417-raydium-rm69380-driver-v4-1-e9c2337d0049@mainlining.org