AP_Frsky_Telem: simplified set_is_flying and moved to header file

libraries/AP_Frsky_Telem/AP_Frsky_Telem.cpp

@@ -889,12 +889,3 @@ void AP_Frsky_Telem::calc_gps_position(void)
         _gps.speed_in_centimeter = 0;
     }
 }
-
-void AP_Frsky_Telem::set_is_flying(bool is_flying)
-{
-    if (is_flying) {
-        _ap.value &= ~AP_LANDCOMPLETE_FLAG; // set land_complete flag to 0
-    } else {
-        _ap.value |= AP_LANDCOMPLETE_FLAG; // set land_complete flag to 1
-    }
-}

libraries/AP_Frsky_Telem/AP_Frsky_Telem.h

@@ -124,7 +124,9 @@ public:
     void update_control_mode(uint8_t mode) { _ap.control_mode = mode; }
 
     // update whether we're flying (used for Plane)
-    void set_is_flying(bool is_flying);
+    // set land_complete flag to 0 if is_flying
+    // set land_complete flag to 1 if not flying
+    void set_is_flying(bool is_flying) { (is_flying) ? (_ap.value &= ~AP_LANDCOMPLETE_FLAG) : (_ap.value |= AP_LANDCOMPLETE_FLAG); }
  
     // update error mask of sensors and subsystems. The mask uses the
     // MAV_SYS_STATUS_* values from mavlink. If a bit is set then it