ARM: omap4-sdp.dts: add display information

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

lcd0: a command mode DSI panel connected to OMAP DSI1 encoder
lcd1: a command mode DSI panel connected to OMAP DSI2 encoder
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>