arm64: dts: rockchip: enable display subsystem on rk3399-firefly

Enable the graphics-related nodes on the rk3399-firefly which makes
it possible to see output on the on-board hdmi output.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-firefly.dts

@@ -255,6 +255,11 @@ &gmac {
 	status = "okay";
 };
 
+&hdmi {
+	ddc-i2c-bus = <&i2c3>;
+	status = "okay";
+};
+
 &i2c0 {
 	clock-frequency = <400000>;
 	i2c-scl-rising-time-ns = <168>;
@@ -728,3 +733,19 @@ &usbdrd_dwc3_1 {
 	status = "okay";
 	dr_mode = "host";
 };
+
+&vopb {
+	status = "okay";
+};
+
+&vopb_mmu {
+	status = "okay";
+};
+
+&vopl {
+	status = "okay";
+};
+
+&vopl_mmu {
+	status = "okay";
+};