[nancy] network api - updated sgraphen[1-4] model to '3com 4510G'

data/grid5000/sites/nancy/network_equipments/sgraphene1.json

data/grid5000/sites/nancy/network_equipments/sgraphene2.json

data/grid5000/sites/nancy/network_equipments/sgraphene3.json

data/grid5000/sites/nancy/network_equipments/sgraphene4.json

generators/input/sites/nancy/net-links/sgraphene1.yaml

generators/input/sites/nancy/net-links/sgraphene2.yaml

generators/input/sites/nancy/net-links/sgraphene3.yaml

generators/input/sites/nancy/net-links/sgraphene4.yaml