dt-bindings: display: samsung,s6d7aa0: Document port

This MIPI-DSI LCD panel must be connected to something, thus add missing
port property, already used in DTS.  Reported by dtbs_check:

  qcom/msm8916-samsung-gt58.dtb: panel@0 (samsung,lsl080al03): 'port' does not match any of the regexes: '^pinctrl-[0-9]+$'

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260306-dt-bindings-display-panel-clean-v1-1-3086eda1efaf@oss.qualcomm.com

Documentation/devicetree/bindings/display/panel/samsung,s6d7aa0.yaml

@@ -44,6 +44,8 @@ properties:
   vmipi-supply:
     description: VMIPI supply, usually 1.8v.
 
+  port: true
+
 required:
   - compatible
   - reg
@@ -65,6 +67,12 @@ examples:
             power-supply = <&display_3v3_supply>;
             reset-gpios = <&gpf0 4 GPIO_ACTIVE_LOW>;
             backlight = <&backlight>;
+
+            port {
+                panel_in: endpoint {
+                    remote-endpoint = <&mdss_dsi0_out>;
+                };
+            };
         };
     };