[facet][box][fvgridgeom] use correct codim for facet mapper

dumux/multidomain/facet/box/fvgridgeometry.hh

@@ -371,7 +371,7 @@ public:
     //! Constructor
     BoxFacetCouplingFVGridGeometry(const GridView gridView)
     : ParentType(gridView)
-    , facetMapper_(gridView, Dune::mcmgLayout(Dune::template Codim<dim-1>()))
+    , facetMapper_(gridView, Dune::mcmgLayout(Dune::template Codim<1>()))
     {}
 
     //! the vertex mapper is the dofMapper