ARM: dts: imx53-cx9020: Group port definitions for the dvi-converter

Group the port definitions of the dvi-converter in a 'ports' node to
make it compliant with the ti,tfp410 binding.

Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>