Copter: Clear the counter when rudder arm operation is disabled

ArduCopter/motors.cpp

@@ -16,6 +16,7 @@ void Copter::arm_motors_check()
     // check if arming/disarm using rudder is allowed
     AP_Arming::RudderArming arming_rudder = arming.get_rudder_arming_type();
     if (arming_rudder == AP_Arming::RudderArming::IS_DISABLED) {
+        arming_counter = 0;
         return;
     }