Replace a check of magic number 4095 with VLAN_N_VID. This
makes it obvious that a later check against VLAN_N_VID is
always true and can be removed.

Change-ID: I28998f127a61a529480ce63d8a07e266f6c63b7b
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>