net/mlx5: fix clang compilation error

net/mlx5: fix clang compilation error

drivers/net/mlx5/mlx5_rxq.c:606:6: error: comparison of constant 4
      with expression of type 'enum hash_rxq_flow_type' is always true
      [-Werror,-Wtautological-constant-out-of-range-compare]
		i != (int)RTE_DIM((*priv->hash_rxqs)[0].special_flow);
		~ ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Clang expects to have an index going upto special_flow size which is
defined by MLX5_MAX_SPECIAL_FLOWS and value is 4.  Comparing to an
unrelated enum where index my be lower cause this compilation issue.

Fixes: 36351ea34b92 ("net/mlx: fix build with icc")
Cc: stable@dpdk.org
Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>