bridge: use either ndo VLAN ops or switchdev VLAN ops to install MASTER vlans

v2:

Move struct switchdev_obj automatics to inner scope where there used.

v1:

To maintain backward compatibility with the existing iproute2 "bridge vlan"
command, let bridge's setlink/dellink handler call into either the port
driver's 8021q ndo ops or the port driver's bridge_setlink/dellink ops.

This allows port driver to choose 8021q ops or the newer
bridge_setlink/dellink ops when implementing VLAN add/del filtering on the
device.  The iproute "bridge vlan" command does not need to be modified.

To summarize using the "bridge vlan" command examples, we have:

1) bridge vlan add|del vid VID dev DEV

Here iproute2 sets MASTER flag.  Bridge's bridge_setlink/dellink is called.
Vlan is set on bridge for port.  If port driver implements ndo 8021q ops,
call those to port driver can install vlan filter on device.  Otherwise, if
port driver implements bridge_setlink/dellink ops, call those to install
vlan filter to device.  This option only works if port is bridged.

2) bridge vlan add|del vid VID dev DEV master

Same as 1)

3) bridge vlan add|del vid VID dev DEV self

Bridge's bridge_setlink/dellink isn't called.  Port driver's
bridge_setlink/dellink is called, if implemented.  This option works if
port is bridged or not.  If port is not bridged, a VLAN can still be
added/deleted to device filter using this variant.

4) bridge vlan add|del vid VID dev DEV master self

This is a combination of 1) and 3), but will only work if port is bridged.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>