OMAP: omap3touchbook: Remove unused lcd stuff

board-omap3touchbook.c adds an LCD device, but the kernel doesn't
contain a driver for the device. So let's remove the unneeded LCD
device.

Cc: Gregoire Gentil <gregoire@gentil.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>