ARM: tegra: tamonten: add the display to the Medcom Wide

Enable the RGB output and add the panel definition to the Medcom Wide
DTS. Also add a label to the backlight defintion to reference it in
the panel definition.

Signed-off-by: Alban Bedel <alban.bedel@avionic-design.de>
Signed-off-by: Stephen Warren <swarren@nvidia.com>