ixgbe: Fix VLAN promisc in relation to SR-IOV

This patch is a follow-on for enabling VLAN promiscuous and allowing the PF
to add VLANs without adding a VLVF entry.  What this patch does is go
through and free the VLVF registers if they are not needed as the VLAN
belongs only to the PF which is the default pool.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>