bridge: Add vlan configuration support

bridge: Add vlan configuration support

Recent kernel patches added support for VLAN filtering on the bridge.
This functionality allows one to turn a basic bridge into a VLAN bridge,
where VLANs dicatate packet forwarding and header transformation.

To configure the VLANs on the bridge and its ports a new command is
added to the 'bridge' utility.

   # bridge vlan add dev eth0 vid 10 pvid untagged brdev
   # bridge vlan add
   # bridge vlan delete dev eth0 vid 10
   # bridge vlan show

This command supports the following flags:
   master - peform the operation on the software bridge device.  This is
	    the default behavior.
   self  -  perform the operation on the hardware associated with the port.
            This flag is required when the device is the bridge device and
	    the configuration is desired on the bridge device itself (not
	    one of the ports).
   pvid  -  Set the PVID (port vlan id) for a given port.  Any untagged
            frames arriving on the port will be assigned to this vlan.
   untagged - Sets the egress policy of for a given vlan.  Default port
            egress policy is tagged.  Set this flag if you wish traffic
            associated with this VLAN to exit the port untagged.

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>