IB/mlx5: Set unique device name on LAG

IB bond device name is now 'mlx5_bond_X', instead of
'mlx5_X'.

Signed-off-by: Aviv Heller <avivh@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>