dt-bindings: display: Add bindings for EBBG FT8719

Add bindings for the EBBG FT8719 6.18" 2246x1080 DSI video mode panel,
which can be found on some Xiaomi Poco F1 phones. The backlight is
managed through the QCOM WLED driver.

Signed-off-by: Joel Selvaraj <jo@jsfamily.in>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/BY5PR02MB7009E821B0D4AC20E11F8F13D9DF9@BY5PR02MB7009.namprd02.prod.outlook.com