ARM: omap3-beagle-xm.dts: add display information

Add DT data for OMAP3 Beagle-xM board. The board has the following displays:

dvi: uses TFP410 encoder to convert DPI to DVI
tv: analog svideo

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