tests: boards: renesas: elc: Add support test app elc for ek_ra4c1

Add support test app ``renesas/elc`` for Renesas ek_ra4c1 board

Signed-off-by: Khoa Nguyen <[email protected]>

Author: khoa-nguyen-18

tests/boards/renesas/elc/boards/ek_ra4c1.overlay

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2025 Renesas Electronics Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		elc-link = &elc;
+	};
+};
+
+&elc {
+	status = "okay";
+};