ArduCopter: fix MAV_CMD_DO_ORBIT double speed bug

orbit_run() was calling update_ms() twice per loop iteration:
once before the turn-count check and once after. Each call
advances the circle angle and ramps angular velocity, resulting
in exactly 2x the requested speed. Fix by removing the redundant
first call and keeping only the single update_ms(0.0f) call
before the attitude/position controller update.

Author: researcher3

ArduCopter/mode_guided.cpp

@@ -1358,8 +1358,7 @@ void ModeGuided::orbit_apply_yaw_behaviour()
 void ModeGuided::orbit_run()
 {
     // call circle controller
-    copter.failsafe_terrain_set_status(copter.circle_nav->update_ms());
-
+    copter.failsafe_terrain_set_status(copter.circle_nav->update_ms(0.0f));
     // check if we've completed the requested number of turns
     if (is_positive(_orbit_turns)) {
         const float turns_completed = fabsf(copter.circle_nav->get_angle_total_rad() / float(M_2PI));
@@ -1370,9 +1369,7 @@ void ModeGuided::orbit_run()
             return;
         }
     }
-
     // call attitude, position and yaw controllers
-    copter.failsafe_terrain_set_status(copter.circle_nav->update_ms(0.0f));
     pos_control->D_update_controller();
     attitude_control->input_thrust_vector_heading(pos_control->get_thrust_vector(), auto_yaw.get_heading());
 }