tests: drivers: adc: test dummy ADC driver

Add a testcase for compiling the dummy `vnd,adc` driver.

Signed-off-by: Jordan Yates <[email protected]>

Author: Jordan Yates

tests/drivers/build_all/adc/boards/qemu_cortex_m3.overlay

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2021, Commonwealth Scientific and Industrial Research
+ * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+ /{
+	test_adc: adc@11112222 {
+		reg = <0x11112222 0x1000>;
+		compatible = "vnd,adc";
+		label = "TEST_ADC";
+		status = "okay";
+		#io-channel-cells = <1>;
+	};
+};

tests/drivers/build_all/adc/testcase.yaml

@@ -58,3 +58,6 @@ tests:
     platform_allow: mec15xxevb_assy6853
     tags: adc_xec
     extra_args: "CONFIG_ADC_XEC=y"
+  drivers.adc.test.build:
+    platform_allow: qemu_cortex_m3
+    tags: adc_test