AC_PosControl: remove out-of-date comments

libraries/AC_AttitudeControl/AC_PosControl.cpp

@@ -505,7 +505,6 @@ void AC_PosControl::accel_to_throttle(float accel_target_z)
 ///
 
 /// set_accel_xy - set horizontal acceleration in cm/s/s
-///     calc_leash_length_xy should be called afterwards
 void AC_PosControl::set_accel_xy(float accel_cmss)
 {
     if (fabsf(_accel_cms-accel_cmss) > 1.0f) {
@@ -516,7 +515,6 @@ void AC_PosControl::set_accel_xy(float accel_cmss)
 }
 
 /// set_speed_xy - set horizontal speed maximum in cm/s
-///     calc_leash_length_xy should be called afterwards
 void AC_PosControl::set_speed_xy(float speed_cms)
 {
     if (fabsf(_speed_cms-speed_cms) > 1.0f) {