rocker: remove support for legacy VLAN ndo ops

Remove support for legacy ndo ops
.ndo_vlan_rx_add_vid/.ndo_vlan_rx_kill_vid.  Rocker will use
bridge_setlink/dellink exclusively for VLAN add/del operations.

The legacy ops are needed if using 8021q driver module to setup VLANs on
the port.  But an alternative exists in using bridge_setlink/delink to
setup VLANs, which doesn't depend on 8021q module.  So rocker will switch
to the newer setlink/dellink ops.  VLANs can added/delete from the port,
regardless if port is bridged or not, using the bridge commands:

	bridge vlan [add|del] vid VID dev DEV self

(Yes, I agree it's confusing to use the "bridge" command to set a VLAN on a
non-bridged port).

Using setlink/dellink over legacy ops let's us handle the stacked driver
case automatically.  It's built-in.  setlink also pass additional flags
(PVID, egress untagged) that aren't available with the legacy ops.

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