ARM: omap4-panda.dts: add display information

Add DT data for OMAP4 Pandaboard. The board has the following displays:

dvi: uses TFP410 encoder to convert DPI to DVI
hdmi: OMAP HDMI output with TPD12S015 ESD/level shifter

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