net: dsa: pass bridge down to drivers

Some DSA drivers may or may not support multiple software bridges on top
of an hardware switch.

It is more convenient for them to access the bridge's net_device for
finer configuration.

Removing the need to craft and access a bitmask also simplifies the
code.

This patch changes the signature of bridge related functions, update DSA
drivers, and removes dsa_slave_br_port_mask.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/dsa/dsa.txt

@@ -524,17 +524,14 @@ Bridge layer
 - port_join_bridge: bridge layer function invoked when a given switch port is
   added to a bridge, this function should be doing the necessary at the switch
   level to permit the joining port from being added to the relevant logical
-  domain for it to ingress/egress traffic with other members of the bridge. DSA
-  does nothing but calculate a bitmask of switch ports currently members of the
-  specified bridge being requested the join
+  domain for it to ingress/egress traffic with other members of the bridge.
 
 - port_leave_bridge: bridge layer function invoked when a given switch port is
   removed from a bridge, this function should be doing the necessary at the
   switch level to deny the leaving port from ingress/egress traffic from the
   remaining bridge members. When the port leaves the bridge, it should be aged
   out at the switch hardware for the switch to (re) learn MAC addresses behind
-  this port. DSA calculates the bitmask of ports still members of the bridge
-  being left
+  this port.
 
 - port_stp_update: bridge layer function invoked when a given switch port STP
   state is computed by the bridge layer and should be propagated to switch