cxgb4: copy vlan_id in ndo_get_vf_config

Copy vlan_id to get it displayed in vf info.

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ganesh Goudhar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>