i40e: Use #define for the VSI connection type

Use #defined VSI connection type values instead of using magic numbers.

Change-ID: I2f6cf7bf394d391e1c0fe61779e9e4ad8858154a
Signed-off-by: Neerav Parikh <neerav.parikh@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>