ARM: dts: omap3-gta04: Add handling for tv output

Add handling for gta04 tv out chain:
venc -> opa362 -> svideo

Use invert-polarity in venc node because opa362
is doing polarity inversion also.

Signed-off-by: Marek Belisko <marek@goldelico.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>