i40iw: user kernel shared files

i40iw_user.h and i40iw_uk.c are used by both user library as well as
kernel requests.

Acked-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>