ARM: dts: omap3-gta04: fixes for tvout / venc

* fix connector compatibility (composite)
* add comment for gpio1 23
* add proper #address-cells
* we use only one venc_out channel for composite

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>