i40iw: Avoid memory leak of CQP request objects

Control Queue Pair (CQP) request objects, which have
not received a completion upon interface close, remain
in memory.

To fix this, identify and free all pending CQP request
objects during destroy CQP OP.

Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Henry Orosco <henry.orosco@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>