rocker: Remove support for bridge FDB learning sync

Currently the rocker driver supports an option for disabling syncing
the hardware learned FDBs with the software bridge. This behavior
breaks the bridge offload model and thus it is removed.

Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>