A FDB entry means that "frames that match this VID and DMAC must be
forwarded to this port".

In the case of dsa_8021q however, the VID is not a single one (and
neither two, as my previous patch assumed). The VID can be set either by
the CPU port (1 tx_vid), or by any of the other front-panel port (n-1
rx_vid's).

Fixes: 93647594 ("net: dsa: sja1105: Hide the dsa_8021q VLANs from the bridge fdb command")
Signed-off-by: NVladimir Oltean <olteanv@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>