EKF: dont check gps_check_fail_status in velocity reset (#761)

In a velocity reset we only used the GPS measurement if _gps_check_fail_status.value was equal to zero. The value of this flag is independent of EKF2_GPS_CHECK so checks can fail even if they are not configured to have any effect.

EKF/ekf_helper.cpp

@@ -53,7 +53,7 @@ bool Ekf::resetVelocity()
 	Vector3f vel_before_reset = _state.vel;
 
 	// reset EKF states
-	if (_control_status.flags.gps && _gps_check_fail_status.value==0) {
+	if (_control_status.flags.gps && isTimedOut(_last_gps_fail_us, (uint64_t)_min_gps_health_time_us)) {
 		ECL_INFO_TIMESTAMPED("reset velocity to GPS");
 		// this reset is only called if we have new gps data at the fusion time horizon
 		_state.vel = _gps_sample_delayed.vel;