samples: drivers: audio: dmic: Add support for nRF7120

Added supported for nRF7120 dmic sample using the AUXPLL.

Signed-off-by: David Jewsbury <[email protected]>

Author: Hi-Im-David

samples/zephyr/drivers/audio/dmic/boards/nrf7120pdk_nrf7120_cpuapp.overlay

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/ {
+	aliases {
+		dmic-dev = &pdm20;
+	};
+};
+
+&pinctrl {
+	pdm20_default_alt: pdm20_default_alt {
+		group1 {
+			psels = <NRF_PSEL(PDM_CLK, 1, 14)>,
+				<NRF_PSEL(PDM_DIN, 1, 12)>;
+		};
+	};
+};
+
+dmic_dev: &pdm20 {
+	status = "okay";
+	pinctrl-0 = <&pdm20_default_alt>;
+	pinctrl-names = "default";
+	clock-source = "ACLK";
+};
+
+&audio_auxpll {
+	nordic,frequency = <NRF_AUXPLL_FREQ_DIV_AUDIO_48K>;
+	status = "okay";
+};