Merge branch 'fix/test-2pncmin' into 'master'

[2pncmin][test] Use dofMapper instead of elementMapper for AMG

See merge request !717

test/porousmediumflow/2pncmin/implicit/test_2pncmin_fv.cc

@@ -156,7 +156,7 @@ int main(int argc, char** argv) try
 
     // the linear solver
     using LinearSolver = AMGBackend<TypeTag>;
-    auto linearSolver = std::make_shared<LinearSolver>(leafGridView, fvGridGeometry->elementMapper());
+    auto linearSolver = std::make_shared<LinearSolver>(leafGridView, fvGridGeometry->dofMapper());
 
     // the non-linear solver
     using NewtonController = PriVarSwitchNewtonController<TypeTag>;