samples: drivers: counter: Add support alarm for ek_ra8p1 cm33

Add support sample ``alarm`` for Renesas ek_ra8p1 cm33

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

Author: khoa-nguyen-18

samples/drivers/counter/alarm/boards/ek_ra8p1_r7ka8p1kflcac_cm33.overlay

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2025 Renesas Electronics Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&agt0 {
+	interrupts = <94 1>, <95 1>;
+	interrupt-names = "agti", "agtcmai";
+	renesas,prescaler = <4>;
+	status = "okay";
+
+	counter0: counter {
+		status = "okay";
+	};
+};