ethdev: fix build with icc
ethdev: fix build with icc

This patch fixes following errors with icc.
  error #188: enumerated type mixed with another type
    return -1;

Fixes: 92d94d3744d7 ("ethdev: attach or detach port")

Reported-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>
Signed-off-by: Tetsuya Mukawa <b347a9f5840345582b30d055e1e99ac6ac7bce3c@igel.co.jp>
Acked-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk