i40e: Communicate VSI id in place of VSI index to the VFs

This does not affect the Virtual channel API as such but it changes the
meaning of what is communicated to the VSI resource struct as vsi_id.
Earlier vsi_idx was being passed in, which was the index in the PF's VSI
array. Now we pass vsi_id as communicated by the FW to the driver.
This will help with future expansion of VF and FW communication.

With this in place now the VF and Virtual channel driver change to move over
to VSI id use is complete and is validated.

Change-ID: I14246ef82b3b3dc1fa76291d2dd0c05d12cedb7c
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>