ARM: dts: at91: sama7g5ek: enable ADC on the board

The ADC controller on the board is fed by a 2.5V reference voltage.
By default the channels #14 and #15 are dedicated to analog input
(marked AN on the board), on the connectors mikrobus1 and mikrobus2.
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20210901123013.329792-11-eugen.hristev@microchip.com

arch/arm/boot/dts/at91-sama7g5ek.dts

@@ -122,6 +122,14 @@ spdif_out: spdif-out {
 	};
 };
 
+&adc {
+	vddana-supply = <&vddout25>;
+	vref-supply = <&vddout25>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_mikrobus1_an_default &pinctrl_mikrobus2_an_default>;
+	status = "okay";
+};
+
 &cpu0 {
 	cpu-supply = <&vddcpu>;
 };