Copter: remove reset of alt target in manual throttle mode

the target was being set to zero only for logging purposes

ArduCopter/Log.cpp

@@ -86,6 +86,12 @@ void Copter::Log_Write_Control_Tuning()
         terr_alt = DataFlash.quiet_nan();
     }
 #endif
+    float des_alt_m = 0.0f;
+    int16_t target_climb_rate_cms = 0;
+    if (!flightmode->has_manual_throttle()) {
+        des_alt_m = pos_control->get_alt_target() / 100.0f;
+        target_climb_rate_cms = pos_control->get_vel_target_z();
+    }
 
     float _target_rangefinder_alt;
     if (target_rangefinder_alt_used) {
@@ -100,13 +106,13 @@ void Copter::Log_Write_Control_Tuning()
         angle_boost         : attitude_control->angle_boost(),
         throttle_out        : motors->get_throttle(),
         throttle_hover      : motors->get_throttle_hover(),
-        desired_alt         : pos_control->get_alt_target() / 100.0f,
+        desired_alt         : des_alt_m,
         inav_alt            : inertial_nav.get_altitude() / 100.0f,
         baro_alt            : baro_alt,
         desired_rangefinder_alt : _target_rangefinder_alt,
         rangefinder_alt     : rangefinder_state.alt_cm,
         terr_alt            : terr_alt,
-        target_climb_rate   : (int16_t)pos_control->get_vel_target_z(),
+        target_climb_rate   : target_climb_rate_cms,
         climb_rate          : climb_rate
     };
     DataFlash.WriteBlock(&pkt, sizeof(pkt));

ArduCopter/mode_acro.cpp

@@ -15,8 +15,6 @@ bool Copter::ModeAcro::init(bool ignore_checks)
            (get_pilot_desired_throttle(channel_throttle->get_control_in(), copter.g2.acro_thr_mid) > copter.get_non_takeoff_throttle())) {
        return false;
    }
-   // set target altitude to zero for reporting
-   pos_control->set_alt_target(0);
 
    return true;
 }

ArduCopter/mode_stabilize.cpp

@@ -12,8 +12,6 @@ bool Copter::ModeStabilize::init(bool ignore_checks)
             (get_pilot_desired_throttle(channel_throttle->get_control_in()) > get_non_takeoff_throttle())) {
         return false;
     }
-    // set target altitude to zero for reporting
-    pos_control->set_alt_target(0);
 
     return true;
 }

ArduCopter/mode_stabilize_heli.cpp

@@ -8,10 +8,6 @@
 // stabilize_init - initialise stabilize controller
 bool Copter::ModeStabilize_Heli::init(bool ignore_checks)
 {
-    // set target altitude to zero for reporting
-    // To-Do: make pos controller aware when it's active/inactive so it can always report the altitude error?
-    pos_control->set_alt_target(0);
-
     // set stab collective true to use stabilize scaled collective pitch range
     copter.input_manager.set_use_stab_col(true);