Pull up following revision(s) (requested by msaitoh in ticket #133):

sys/dev/pci/ixgbe/ixgbe.c: revision 1.200
sys/dev/pci/ixgbe/ixgbe.c: revision 1.201
sys/dev/pci/ixgbe/ixv.c: revision 1.126
sys/dev/pci/ixgbe/ixv.c: revision 1.127
sys/net/if_vlan.c: revision 1.142
sys/net/if_vlan.c: revision 1.143
sys/net/if_vlan.c: revision 1.144
sys/net/if_vlan.c: revision 1.145
sys/net/if_vlan.c: revision 1.146

Check ec_capenable instead of ec_capabilities to control TX side of VLAN HW
tagging correctly.
XXX pullup-9

Add missing IFNET_LOCK() and IFNET_UNLOCK() in vlan_config().
XXX pullup-9

Fix a bug that VLAN HW "tagging" enable/disable may not reflect correctly.
  - Always call ec_vlan_cb() if it exists.
  - Some (or all?) ethernet drivers don't enable HW tagging if no any vlan is
    attached. ixgbe is one of them. Check the the transition and update
    VLAN HW tagging function.
XXX pullup-9

Use ETHER_LOCK()/ETHER_UNLOCK() suggested by knakahara.
- kmem_alloc(,KM_SLEEP) never return NULL, so remove NULL check.
- VLAN ID is never duplicated, so break the loop when found. Also move
  kmen_free() outside of ETHER_LOCK(ec)/ETHER_UNLOCK(ec) to reduce the hold
  time. suggested by ozaki-r.
- Whitespace fix.

(martin)