There is only one check left for that attribute in rtldsa_port_mdb_add().
Split the consumer into device specific implementations and remove the
attribute from the private structure.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/22794
Signed-off-by: Robert Marko <robimarko@gmail.com>