dt-bindings: display: convert olimex,lcd-olinuxino to DT Schema

v2:
  - use "ic2" node name in example (Rob)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Stefan Mavrodiev <stefan@olimex.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200408195109.32692-36-sam@ravnborg.org