Copter: only save autotune gains if disarmed in autotue

ArduCopter/mode.h

@@ -499,6 +499,7 @@ public:
 
     void save_tuning_gains();
     void stop();
+    void reset();
 
 protected:
 

ArduCopter/mode_autotune.cpp

@@ -173,4 +173,9 @@ void Copter::ModeAutoTune::stop()
     copter.autotune.stop();
 }
 
+void Copter::ModeAutoTune::reset()
+{
+    copter.autotune.reset();
+}
+
 #endif  // AUTOTUNE_ENABLED == ENABLED

ArduCopter/motors.cpp

@@ -266,7 +266,11 @@ void Copter::init_disarm_motors()
 
 #if AUTOTUNE_ENABLED == ENABLED
     // save auto tuned parameters
-    mode_autotune.save_tuning_gains();
+    if (control_mode == AUTOTUNE) {;
+        mode_autotune.save_tuning_gains();
+    } else {
+        mode_autotune.reset();
+    }
 #endif
 
     // we are not in the air