i40e: allow one more vector for VFs

The number of vectors per VF as reported by the hardware does not
include vector 0, so we need to account for this when checking to
see if the VF is configuring a valid vector.

Change-Id: I051d8bebae8f4722239f5a3fa5e1de4cf0f4e817
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>