net/mlx5: fix icc build

net/mlx5: fix icc build

Remove the second declaration of device_attr [1] inside the loop as well as
the query_device_ex() which has already been done outside of the loop.

[1] https://dpdk.org/ml/archives/dev/2018-March/091744.html

Fixes: 9a761de8ea14 ("net/mlx5: flow counter support")
Cc: stable@dpdk.org
Reported-by: Ferruh Yigit <ferruh.yigit@intel.com>
Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>
Tested-by: Ferruh Yigit <ferruh.yigit@intel.com>