arm64: dts: renesas: aistarvision-mipi-adapter-2.1: Fix CSI40 ports

arm64: dts: renesas: aistarvision-mipi-adapter-2.1: Fix CSI40 ports

Fix the DTS schema by explicitly stating that the input is port@0. This
fixes a schema validation error but has no runtime effect as the default
port number is 0 if not specified.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20210421150221.3202955-2-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>