ARM: dts: sun9i: cubieboard4: Enable Reduced Serial Bus controller

The Reduced Serial Bus (RSB) controller is used to talk to the 3
companion ICs (2 PMICs, 1 RTC/codec IC) on the board.
Signed-off-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun9i-a80-cubieboard4.dts

@@ -118,6 +118,10 @@
 	status = "okay";
 };
 
+&r_rsb {
+	status = "okay";
+};
+
 &uart0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart0_pins_a>;