Plane: fixed chute release on low value of RC option

only release on flag high
fixes #18843

ArduPlane/RC_Channel.cpp

@@ -311,7 +311,9 @@ case AUX_FUNC::ARSPD_CALIBRATE:
 
     case AUX_FUNC::PARACHUTE_RELEASE:
 #if PARACHUTE == ENABLED
+        if (ch_flag == AuxSwitchPos::HIGH) {
             plane.parachute_manual_release();
+        }
 #endif
         break;