dt-bindings: display: simple: add Rocktech RK043FN48H

Add compatible to panel-simple for Rocktech Displays Limited
RK043FN48H 4.3" 480x272 LCD-TFT panel.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230607063139.621351-5-dario.binacchi@amarulasolutions.com