312x: add key dts node

arch/arm/boot/dts/rk3036-sdk.dts

@@ -197,6 +197,59 @@
 };
 
 
+&adc {
+	status = "okay";
+
+	key {
+		compatible = "rockchip,key";
+		io-channels = <&adc 1>;
+
+		vol-up-key {
+			linux,code = <115>;
+			label = "volume up";
+			rockchip,adc_value = <1>;
+		};
+
+		vol-down-key {
+			linux,code = <114>;
+			label = "volume down";
+			rockchip,adc_value = <170>;
+		};
+		
+		power-key {
+			gpios = <&gpio0 GPIO_A5 GPIO_ACTIVE_LOW>;
+			linux,code = <116>;
+			label = "power";
+			gpio-key,wakeup;
+		};
+
+		menu-key {
+			linux,code = <59>;
+			label = "menu";
+			rockchip,adc_value = <355>;
+		};
+
+		home-key {
+			linux,code = <102>;
+			label = "home";
+			rockchip,adc_value = <746>;
+		};
+
+		back-key {
+			linux,code = <158>;
+			label = "back";
+			rockchip,adc_value = <560>;
+		};
+
+		camera-key {
+			linux,code = <212>;
+			label = "camera";
+			rockchip,adc_value = <450>;
+		};
+	};
+};
+
+
 &i2c1 {
 	status = "okay";
         rtc@51 {