snippets: Add 54lm20 to the WiFi ext-flash snippet

Added board files dedicated to 54lm20 boards to allow building the
ext-flash snippet.

Signed-off-by: Arkadiusz Balys <arkadiusz.balys@nordicsemi.no>

Author: ArekBalysNordic

snippets/nrf70-fw-patch-ext-flash/boards/nrf54lm20dk_nrf54lm20a_cpuapp.conf

@@ -0,0 +1,11 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_GPIO=y
+CONFIG_SPI=y
+CONFIG_SPI_NOR=y
+CONFIG_SPI_NOR_SFDP_DEVICETREE=y
+CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

snippets/nrf70-fw-patch-ext-flash/boards/nrf54lm20dk_nrf54lm20a_cpuapp.overlay

@@ -0,0 +1,8 @@
+/* Copyright (c) 2026 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+&spi00 {
+	status = "okay";
+};

snippets/nrf70-fw-patch-ext-flash/boards/nrf54lm20dk_nrf54lm20b_cpuapp.conf

@@ -0,0 +1,11 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_GPIO=y
+CONFIG_SPI=y
+CONFIG_SPI_NOR=y
+CONFIG_SPI_NOR_SFDP_DEVICETREE=y
+CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

snippets/nrf70-fw-patch-ext-flash/boards/nrf54lm20dk_nrf54lm20b_cpuapp.overlay

@@ -0,0 +1,8 @@
+/* Copyright (c) 2026 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+&spi00 {
+	status = "okay";
+};

snippets/nrf70-fw-patch-ext-flash/fw-patch-ext-flash.overlay

@@ -10,6 +10,8 @@
 };
 
 &mx25r64 {
+	status = "okay";
+
 	partitions {
 		compatible = "fixed-partitions";
 		#address-cells = <1>;

snippets/nrf70-fw-patch-ext-flash/snippet.yml

@@ -8,3 +8,9 @@ boards:
   nrf7002dk/nrf5340/cpuapp:
     append:
       EXTRA_CONF_FILE: boards/nrf7002dk_nrf5340_cpuapp.conf
+  nrf54lm20dk/nrf54lm20a/cpuapp:
+    append:
+      EXTRA_CONF_FILE: boards/nrf54lm20dk_nrf54lm20a_cpuapp.conf
+  nrf54lm20dk/nrf54lm20b/cpuapp:
+    append:
+      EXTRA_CONF_FILE: boards/nrf54lm20dk_nrf54lm20b_cpuapp.conf