ARM: dts: sbc-t3x: add DVI display data

Add DSS related pinmux and display data nodes required to support
DVI video out on SBC-T3530, SBC-T3730 and SBC-T3517.

Signed-off-by: Dmitry Lifshitz <lifshitz@compulab.co.il>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Tony Lindgren <tony@atomide.com>