samples: drivers: counter: add nRF54L09 config

Added build configuration for nRF54L09.

Signed-off-by: Rafał Kuźnia <[email protected]>

Author: e-rk

samples/drivers/counter/alarm/boards/nrf54l09pdk_nrf54l09_cpuapp.overlay

@@ -0,0 +1,9 @@
+/ {
+	chosen {
+		counter = &timer24;
+	};
+};
+
+&timer24 {
+	status = "okay";
+};