AP_NavEKF2: use NEW_NOTHROW for new(std::nothrow)

libraries/AP_NavEKF2/AP_NavEKF2_core.cpp

@@ -99,7 +99,7 @@ bool NavEKF2_core::setup_core(uint8_t _imu_index, uint8_t _core_index)
         }
 
         // try to instantiate
-        yawEstimator = new EKFGSF_yaw();
+        yawEstimator = NEW_NOTHROW EKFGSF_yaw();
         if (yawEstimator == nullptr) {
             GCS_SEND_TEXT(MAV_SEVERITY_CRITICAL, "EKF2 IMU%uGSF: allocation failed",(unsigned)imu_index);
             return false;