i40e: trivial: cleanup use of pf->hw

This patch makes use of a pointer called hw consistent
in the i40e_remove function.

Change-ID: Idacc7ff0a09a68289c57457a78618bf5497de077
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>