RDMA/i40iw: fix duplicated code for different branches

Refactor code to avoid identical code for different branches.

Addresses-Coverity-ID: 1357356
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>