[nrf fromlist] tests: drivers: adc: Enable adc test for nrf9280 iron

Added overlay for nrf9280 cpuapp iron board.
Modified overlay for nrf9280 cpuapp board to use common dtsi.

Upstream PR #: 90756
Signed-off-by: Aymen LAOUINI <aymen.laouini@nordicsemi.no>

Author: ayla-nordicsemi

tests/drivers/adc/adc_api/boards/nrf9280pdk_nrf9280_common.dtsi

@@ -0,0 +1,43 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ */
+
+/ {
+	zephyr,user {
+		io-channels = <&adc 0>, <&adc 1>, <&adc 2>;
+	};
+};
+
+&adc {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	channel@0 {
+		reg = <0>;
+		zephyr,gain = "ADC_GAIN_1_2";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)>;
+		zephyr,input-positive = <NRF_SAADC_AIN1>;
+		zephyr,resolution = <10>;
+	};
+
+	channel@1 {
+		reg = <1>;
+		zephyr,gain = "ADC_GAIN_2";
+		zephyr,reference = "ADC_REF_EXTERNAL0";
+		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)>;
+		zephyr,input-positive = <NRF_SAADC_AIN3>;
+		zephyr,resolution = <10>;
+	};
+
+	channel@2 {
+		reg = <2>;
+		zephyr,gain = "ADC_GAIN_2_3";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)>;
+		zephyr,input-positive = <NRF_SAADC_AIN2>;
+		zephyr,resolution = <10>;
+	};
+};

tests/drivers/adc/adc_api/boards/nrf9280pdk_nrf9280_cpuapp.overlay

@@ -1,43 +1,7 @@
 /*
  * SPDX-License-Identifier: Apache-2.0
  *
- * Copyright (c) 2024 Nordic Semiconductor ASA
+ * Copyright (c) 2025 Nordic Semiconductor ASA
  */
 
-/ {
-	zephyr,user {
-		io-channels = <&adc 0>, <&adc 1>, <&adc 2>;
-	};
-};
-
-&adc {
-	#address-cells = <1>;
-	#size-cells = <0>;
-
-	channel@0 {
-		reg = <0>;
-		zephyr,gain = "ADC_GAIN_1_2";
-		zephyr,reference = "ADC_REF_INTERNAL";
-		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)>;
-		zephyr,input-positive = <NRF_SAADC_AIN1>;
-		zephyr,resolution = <10>;
-	};
-
-	channel@1 {
-		reg = <1>;
-		zephyr,gain = "ADC_GAIN_2";
-		zephyr,reference = "ADC_REF_EXTERNAL0";
-		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)>;
-		zephyr,input-positive = <NRF_SAADC_AIN3>;
-		zephyr,resolution = <10>;
-	};
-
-	channel@2 {
-		reg = <2>;
-		zephyr,gain = "ADC_GAIN_1_2";
-		zephyr,reference = "ADC_REF_INTERNAL";
-		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)>;
-		zephyr,input-positive = <NRF_SAADC_AIN2>;
-		zephyr,resolution = <10>;
-	};
-};
+#include "nrf9280pdk_nrf9280_common.dtsi"

tests/drivers/adc/adc_api/boards/nrf9280pdk_nrf9280_cpuapp_iron.overlay

@@ -0,0 +1,7 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ */
+
+#include "nrf9280pdk_nrf9280_common.dtsi"