HD702E lcd is FriendlyELEC developed eDP LCD panel with 800x1280
resolution. It has built in Goodix, GT9271 captive touchscreen
with backlight adjustable via PWM.

Add dt-bindings documentation for it.
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190507130708.11255-1-jagan@amarulasolutions.com