media: dt-bindings: atmel,isc: Drop unneeded unevaluatedProperties

The 'port' node schema has both 'additionalProperties' and
'unevaluatedProperties', but only one is necessary.
'additionalProperties' works here, so drop 'unevaluatedProperties' and
move 'additionalProperties' next to the $ref.

Link: https://lore.kernel.org/r/20221207204406.2810864-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>