net/mlx4: Change ENOTSUPP to EOPNOTSUPP

As ENOTSUPP is specific to NFS, change the return error value to
EOPNOTSUPP in various places in the mlx4 driver.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Suggested-by: Yotam Gigi <yotamg@mellanox.com>
Reviewed-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>