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

Describe how the DSA subsystem works, its design principles,
limitations, and describe in details how to implement a DSA switch
driver.
Acked-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NScott Feldman <sfeldma@gmail.com>
Reviewed-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>