mlxsw: spectrum: Disable MAC learning for ovs port

Learning is currently enabled for ports which are OVS slaves -
even though OVS doesn't need this indication.
Since we're not associating a fid with the port, HW would continuously
notify driver of learned [& aged] MACs which would be logged as errors.

Fixes: 2b94e58d ("mlxsw: spectrum: Allow ports to work under OVS master")
Signed-off-by: Yuval Mintz <yuvalm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>