drm/panel: simple: Add Netron DY E231732

The E231732 is a 7" panel with a resolution of 1024x600.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
[treding@nvidia.com: add missing device tree binding]
Signed-off-by: Thierry Reding <treding@nvidia.com>