drm/panel: panel-simple: add LOGIC Technologies LTTD800480070-L2RT panel

Add support for the Logic Technologies LTTD800x480 L2RT 7" 800x480 TFT
Resistive Touch Module.

Signed-off-by: Søren Andersen <san@skov.dk>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210930100501.15690-3-o.rempel@pengutronix.de