media: dt-binding: media: hynix,hi846: use $defs/port-base port description

media: dt-binding: media: hynix,hi846: use $defs/port-base port description

This fixes "make dt_binding_check":

    Documentation/devicetree/bindings/media/i2c/hynix,hi846.example.dt.yaml:
camera@20: port:endpoint: Unevaluated properties are not allowed
('link-frequencies', 'data-lanes' were unexpected)
    From schema: Documentation/devicetree/bindings/media/i2c/hynix,hi846.yaml

[Sakari Ailus: Reword commit message]

Fixes: f3ce7200ca18 ("media: dt-bindings: media: document SK Hynix Hi-846 MIPI CSI-2 8M pixel sensor")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>