Filtering identifiers (FIDs) are unique identifers of bridge instances
in the hardware.

Add the SFMR register, which is responsible for the creation and
configuration of these FIDs.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>