i40iw: Set 128B as the only supported RQ WQE size

RQ WQE size other than 128B is not supported.  Correct
RQ size calculation to use 128B only.

Since this breaks ABI, add additional code to
provide compatibility with v4 user provider, libi40iw.

Signed-off-by: Chien Tin Tung <chien.tin.tung@intel.com>
Signed-off-by: Henry Orosco <henry.orosco@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>