arm: sun7i: cubietruck: Enable the i2c controllers

The Cubietruck makes use of the first three i2c controllers found on the
Allwinner A20; i2c-0 is used internally for the PMIC, i2c-1 is exposed on
the board headers, and i2c-2 is used for DDC on the VGA connector. This
patch enables them in the device tree.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun7i-a20-cubietruck.dts

@@ -33,6 +33,24 @@ uart0: serial@01c28000 {
 			pinctrl-0 = <&uart0_pins_a>;
 			status = "okay";
 		};
+
+		i2c0: i2c@01c2ac00 {
+			pinctrl-names = "default";
+			pinctrl-0 = <&i2c0_pins_a>;
+			status = "okay";
+		};
+
+		i2c1: i2c@01c2b000 {
+			pinctrl-names = "default";
+			pinctrl-0 = <&i2c1_pins_a>;
+			status = "okay";
+		};
+
+		i2c2: i2c@01c2b400 {
+			pinctrl-names = "default";
+			pinctrl-0 = <&i2c2_pins_a>;
+			status = "okay";
+		};
 	};
 
 	leds {