dt-bindings: display: tegra: Document Tegra20 HDMI port

Tegra HDMI can be modeled using an OF graph. Reflect this in the
bindings.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-hdmi.yaml

@@ -82,6 +82,10 @@ properties:
     description: phandle of a display panel
     $ref: /schemas/types.yaml#/definitions/phandle
 
+  port:
+    description: HDMI output port for connection to HDMI connector or bridge
+    $ref: /schemas/graph.yaml#/properties/port
+
   "#sound-dai-cells":
     const: 0
 
@@ -97,8 +101,13 @@ required:
   - reset-names
   - pll-supply
   - vdd-supply
-  - nvidia,ddc-i2c-bus
-  - nvidia,hpd-gpio
+
+anyOf:
+  - required:
+      - nvidia,ddc-i2c-bus
+      - nvidia,hpd-gpio
+  - required:
+      - port
 
 examples:
   - |