media: rcar-vin: remove generic gen3 compatible string

The compatible string "renesas,rcar-gen3-vin" was added before the
Gen3 driver code was added but it's not possible to use. Each SoC in the
Gen3 series require SoC specific knowledge in the driver to function.
Remove it before it is added to any device tree descriptions.
Signed-off-by: NNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: NSimon Horman <horms+renesas@verge.net.au>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/devicetree/bindings/media/rcar_vin.txt

@@ -24,7 +24,6 @@ on Gen3 platforms to a CSI-2 receiver.
    - "renesas,vin-r8a77970" for the R8A77970 device
    - "renesas,rcar-gen2-vin" for a generic R-Car Gen2 or RZ/G1 compatible
      device.
-   - "renesas,rcar-gen3-vin" for a generic R-Car Gen3 compatible device.
 
    When compatible with the generic version nodes must list the
    SoC-specific version corresponding to the platform first