The different port@ entries of the adv7482 nodes shall be encapsulated
in a ports node, add one.  This change does not change how the driver
parses the DT and no driver change is needed.

The change however makes it possible to validate the source files with a
correct json-schema.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20211012183431.718691-1-niklas.soderlund+renesas@ragnatech.seSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>