ARM: dts: at91: sama5d27_som1_ek: add adc regulators

Add fixed regulators for the ADC. This board does not have
a programmable PMIC, but fixed regulators.
Adding them to DT so the ADC can probe correctly.
Tested-by: NSwapna Gurumani <swapna.gurumani@microchip.com>
Signed-off-by: NLudovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: NEugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>

arch/arm/boot/dts/at91-sama5d27_som1_ek.dts

@@ -283,6 +283,13 @@
 				status = "okay";
 			};
 
+			adc: adc@fc030000 {
+				vddana-supply = <&vddana>;
+				vref-supply = <&advref>;
+
+				status = "disabled";
+			};
+
 			pinctrl@fc038000 {
 
 				pinctrl_can1_default: can1_default {
@@ -549,4 +556,39 @@
 			linux,default-trigger = "heartbeat";
 		};
 	};
+
+	vddin_3v3: fixed-regulator-vddin_3v3 {
+		compatible = "regulator-fixed";
+
+		regulator-name = "VDDIN_3V3";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-always-on;
+		regulator-boot-on;
+		status = "okay";
+	};
+
+	vddana: fixed-regulator-vddana {
+		compatible = "regulator-fixed";
+
+		regulator-name = "VDDANA";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-always-on;
+		regulator-boot-on;
+		vin-supply = <&vddin_3v3>;
+		status = "okay";
+	};
+
+	advref: fixed-regulator-advref {
+		compatible = "regulator-fixed";
+
+		regulator-name = "advref";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-always-on;
+		regulator-boot-on;
+		vin-supply = <&vddana>;
+		status = "okay";
+	};
 };