dt-bindings: drm/bridge: ti-sn65dsi86: Add aux-bus child

The patch ("dt-bindings: drm: Introduce the DP AUX bus") talks about
how using the DP AUX bus is better than learning how to slice
bread. Let's add it to the ti-sn65dsi86 bindings.

Signed-off-by: Douglas Anderson <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.3.I98bf729846c37c4c143f6ab88b1e299280e2fe26@changeid

Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml

···
     const: 1
     description: See ../../pwm/pwm.yaml for description of the cell formats.
 
+  aux-bus:
+    $ref: /schemas/display/dp-aux-bus.yaml#
+
   ports:
     $ref: /schemas/graph.yaml#/properties/ports
 
···
 
           port@1 {
             reg = <1>;
-            endpoint {
+            sn65dsi86_out: endpoint {
               remote-endpoint = <&panel_in_edp>;
+            };
+          };
+        };
+
+        aux-bus {
+          panel {
+            compatible = "boe,nv133fhm-n62";
+            power-supply = <&pp3300_dx_edp>;
+            backlight = <&backlight>;
+            hpd-gpios = <&sn65dsi86_bridge 2 GPIO_ACTIVE_HIGH>;
+
+            port {
+              panel_in_edp: endpoint {
+                remote-endpoint = <&sn65dsi86_out>;
+              };
             };
           };
         };