uart1: working rts/cts on arduino header

boards/nrf5340dk_nrf5340_cpuapp.overlay

@@ -1,5 +1,16 @@
 /* SPDX-License-Identifier: Apache-2.0 */
 
+/ {
+    host_interface {
+        compatible = "gpio-outputs";
+        status = "okay";
+        timesync: pin_0 {
+		    gpios = <&arduino_header 10 GPIO_ACTIVE_HIGH>;
+            label = "Controller to host timesync pin";
+        };
+    };
+};
+
 &uart0 {
 	compatible = "nordic,nrf-uarte";
 	current-speed = <1000000>;