i40iw: Add 2MB page support

Add support to allow each independent memory region to
be configured for 2MB page size in addition to 4KB
page size.

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>