i40iw: Code cleanup, remove check of PBLE pages

Remove check for zero 'pages' of unallocated pbles calculated in
add_pble_pool(); as it can never be true.

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>