i40iw: add hw and utils files

i40iw_hw.c, i40iw_utils.c and i40iw_osdep.h are files to handle
interrupts and processing.

Changes since v1:
        Cleanup/removed some macros reported by Christoph Hellwig.

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>