Parachute: set servo or relay to off position on every update

This resolves the issue of the parachute servo's position not being
initialised to the off position due to an ordering problem of the
auxiliary servos being initialised after the parachute object.

libraries/AP_Parachute/AP_Parachute.cpp

@@ -83,7 +83,7 @@ void AP_Parachute::release()
 void AP_Parachute::update()
 {
     // exit immediately if not enabled or parachute not to be released
-    if (_enabled <= 0 || _release_time == 0) {
+    if (_enabled <= 0) {
         return;
     }
 
@@ -91,7 +91,7 @@ void AP_Parachute::update()
     uint32_t time_diff = hal.scheduler->millis() - _release_time;
 
     // check if we should release parachute
-    if (!_released) {
+    if ((_release_time != 0) && !_released) {
         if (time_diff >= AP_PARACHUTE_RELEASE_DELAY_MS) {
             if (_release_type == AP_PARACHUTE_TRIGGER_TYPE_SERVO) {
                 // move servo
@@ -102,7 +102,7 @@ void AP_Parachute::update()
             }
             _released = true;
         }
-    }else if (time_diff >= AP_PARACHUTE_RELEASE_DELAY_MS + AP_PARACHUTE_RELEASE_DURATION_MS) {
+    }else if ((_release_time == 0) || time_diff >= AP_PARACHUTE_RELEASE_DELAY_MS + AP_PARACHUTE_RELEASE_DURATION_MS) {
         if (_release_type == AP_PARACHUTE_TRIGGER_TYPE_SERVO) {
             // move servo back to off position
             RC_Channel_aux::set_radio(RC_Channel_aux::k_parachute_release, _servo_off_pwm);