drm/panel-simple: fix connector type for LogicPD Type28 Display

The LogicPD Type28 display used by several Logic PD products has not
worked since v5.6.

The connector type for the LogicPD Type 28 display is missing and
drm_panel_bridge_add() requires connector type to be set.

Signed-off-by: Adam Ford <aford173@gmail.com>
Fixes: 0d35408a ("drm/panel: simple: Add Logic PD Type 28 display support")
Cc: Adam Ford <aford173@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.6+
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200615131934.12440-1-aford173@gmail.com