ArduSub/mode_acro: fix bug for dealing throttle from pilot

Author: xianglunkai

ArduSub/mode_acro.cpp

@@ -33,7 +33,7 @@ void ModeAcro::run()
     attitude_control->input_rate_bf_roll_pitch_yaw_cds(target_roll, target_pitch, target_yaw);
 
     // output pilot's throttle without angle boost
-    attitude_control->set_throttle_out(channel_throttle->norm_input(), false, g.throttle_filt);
+    attitude_control->set_throttle_out((channel_throttle->norm_input() + 1.0f) / 2.0f, false, g.throttle_filt);
 
     //control_in is range 0-1000
     //radio_in is raw pwm value