i40e/i40evf: rename vf_offload_flags to vf_cap_flags in struct virtchnl_vf_resource

The current name of vf_offload_flags indicates that the bitmap is
limited to offload related features. Make this more generic by renaming
it to vf_cap_flags, which allows for other capabilities besides
offloading to be added.

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>