arm: spear6xx: add DT description of the ADC on SPEAr600

The SPEAr600 has a built-in ADC, which already has a Device Tree binding
described in
Documentation/devicetree/bindings/staging/iio/adc/spear-adc.txt. This
commit adds the description in the SPEAr600 Device Tree of this ADC
device.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/boot/dts/spear600.dtsi

@@ -204,6 +204,14 @@ timer@f0000000 {
 				interrupt-parent = <&vic0>;
 				interrupts = <16>;
 			};
+
+			adc: adc@d820b000 {
+				compatible = "st,spear600-adc";
+				reg = <0xd820b000 0x1000>;
+				interrupt-parent = <&vic1>;
+				interrupts = <6>;
+				status = "disabled";
+			};
 		};
 	};
 };