arm64: dts: rockchip: add rk3399 eDP HPD pinctrl

We haven't enabled eDP support yet, but we might as well describe the
pin now.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399.dtsi

@@ -1436,6 +1436,13 @@ clk_32k: clk-32k {
 			};
 		};
 
+		edp {
+			edp_hpd: edp-hpd {
+				rockchip,pins =
+					<4 23 RK_FUNC_2 &pcfg_pull_none>;
+			};
+		};
+
 		gmac {
 			rgmii_pins: rgmii-pins {
 				rockchip,pins =