tests/fs/littlefs: Allow tests to run on the nrf54l15pdk

The commit adds nrf54l15pdk/nrf54l15/cpuapp to list of allowed
platforms for default test configuration.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

tests/subsys/fs/littlefs/boards/nrf54l15pdk_nrf54l15_cpuapp.overlay

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/delete-node/ &slot0_ns_partition;
+/delete-node/ &slot1_partition;
+/delete-node/ &slot1_ns_partition;
+
+&cpuapp_rram {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		small_partition: partition@67000 {
+			label = "small";
+			reg = <0x00067000 0x00010000>;
+		};
+	};
+};

tests/subsys/fs/littlefs/testcase.yaml

@@ -15,6 +15,7 @@ common:
 tests:
   filesystem.littlefs.default:
     timeout: 60
+    platform_allow: nrf54l15pdk/nrf54l15/cpuapp
   filesystem.littlefs.custom:
     timeout: 180
     extra_configs: