nitrogen6x: display: add support for LG-9.7 LVDS display

Add support for LG 9.7" LVDS panel (1024x768) with integrated eGalax
touch screen.

Note that this panel differs only slightly from the Hannstar XGA panel
(margins).

No auto-detection is available because it shares the same touch controller
as the Hannstar-XGA display, so you'll need to configure it through the
'panel' environment variable:

        U-Boot > setenv panel LG-9.7
        U-Boot > saveenv && reset

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>