mlxsw: spectrum: Mark port as active before registering it

Commit bbf2a475 ("mlxsw: spectrum: Initialize ports at the end of
init sequence") moved ports initialization to the end of the init
sequence, which means ports are the first to be removed during fini.

Since the FDB delayed work is still active when ports are removed it's
possible for it to process FDB notifications of inactive ports,
resulting in a warning message.

Fix that by marking ports as inactive only after unregistering them. The
NETDEV_UNREGISTER event will invoke bridge's driver port removal
sequence that will cause the FDB (and FDB notifications) to be flushed.

Fixes: bbf2a475

 ("mlxsw: spectrum: Initialize ports at the end of init sequence")
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>