arm64: dts: r8a7795: salvator-x: Add DU LVDS output endpoint

Declaring the endpoint makes LVDS enablement easier by just including
the corresponding panel's dtsi file.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7795-salvator-x.dts

@@ -191,6 +191,10 @@
 				remote-endpoint = <&adv7123_in>;
 			};
 		};
+		port@3 {
+			lvds_connector: endpoint {
+			};
+		};
 	};
 };