mlxsw: spectrum: Set bridge status in appropriate functions

Set the bridge status of physical ports in the appropriate functions, to
be consistent with LAG join/leave and vPorts joining/leaving bridge.

Also, remove the error messages in these two functions, as we already
emit errors in both the single functions they call.

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>