Use FEInterface::n_dofs_at_node() in DofMap::reinit()
Use FEInterface::n_dofs_at_node() in DofMap::reinit()

The code was correct previously, this change just saves a manual calculation.

jwpeterson/libmesh,jwpeterson/libmesh,libMesh/libmesh,dschwen/libmesh,libMesh/libmesh,dschwen/libmesh,jwpeterson/libmesh,dschwen/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,dschwen/libmesh,libMesh/libmesh,BalticPinguin/libmesh,dschwen/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,dschwen/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,roystgnr/libmesh,roystgnr/libmesh,dschwen/libmesh,libMesh/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,jwpeterson/libmesh,libMesh/libmesh,jwpeterson/libmesh,libMesh/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,libMesh/libmesh,jwpeterson/libmesh,libMesh/libmesh,dschwen/libmesh,roystgnr/libmesh