dt-bindings: media: Fix graph 'unevaluatedProperties' related warnings

dt-bindings: media: Fix graph 'unevaluatedProperties' related warnings

The graph schema doesn't allow custom properties on endpoint nodes for
'#/properties/port' and '#/$defs/port-base' should be used instead. This
doesn't matter until 'unevaluatedProperties' support is implemented.

Cc: Eugen Hristev <eugen.hristev@microchip.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Cc: Ramesh Shanmugasundaram <rashanmu@gmail.com>
Cc: linux-media@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210719194850.2410511-1-robh@kernel.org