net: dsa: b53: Add JOIN_ALL_VLAN support

In order to migrate the bcm_sf2 driver over to the b53 driver for most
VLAN/FDB/bridge operations, we need to add support for the "join all
VLANs" register and behavior which allows us to make a given port join
all VLANs and avoid setting specific VLAN entries when it is leaving the
bridge.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>