i40e/i40evf: Explicitly assign enum index for VSI type

Ran into an issue where PF's VSI type list was different from VF's,
which was resulted in different enum index. The VSI type list can
be different depending on what build flag is used for PF and VF.

The change is to explicitly assign enum index for each VSI type
so that PF and VF always reference to the same VSI type event if the
enum lists are different.

Change-ID: I8c0e5fdb515f324f7964df863a458073cf467e57
Signed-off-by: Serey Kong <serey.kong@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>