dt-bindings: display: vc4: Document BCM2711 VC5

The BCM2711 comes with a new VideoCore. Add a compatible for it.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Rob Herring <robh+dt@kernel.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/1075091c50b378505a9a89f760af11f0e1e26e5b.1599120059.git-series.maxime@cerno.tech

Documentation/devicetree/bindings/display/brcm,bcm2835-vc4.yaml

@@ -17,6 +17,7 @@ description: >
 properties:
   compatible:
     enum:
+      - brcm,bcm2711-vc5
       - brcm,bcm2835-vc4
       - brcm,cygnus-vc4