Copter: log flight mode after arming

ArduCopter/motors.pde

@@ -204,6 +204,9 @@ static void init_arm_motors()
     // log arming to dataflash
     Log_Write_Event(DATA_ARMED);
 
+    // log flight mode in case it was changed while vehicle was disarmed
+    Log_Write_Mode(control_mode);
+
     // reenable failsafe
     failsafe_enable();
 }