i40e: remove unnecessary string copy operations

Save a little stack space and remove unnecessary strncpy() with a little
string pointer.

Change-ID: Id2719d34710bfc273d3bb445fec085cd04276e88
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>