Followup to UBL Hilbert

Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp

 
       best = do_furthest  ? find_furthest_invalid_mesh_point()
                           : TERN(UBL_HILBERT_CURVE,
-                              next_point_in_grid(),
+                              find_next_mesh_point(),
                               find_closest_mesh_point_of_type(INVALID, nearby, true)
                             );