Document the 1080x2340 Visionox R66451 AMOLED DSI panel bindings

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230516-b4-r66451-panel-driver-v2-1-9c8d5eeef579@quicinc.com