mlxsw: spectrum: Allow ports to work under OVS master

>From now on, a port can become a slave of OVS master. All vlans
are enabled, STP state is set to "forwarding". It is up to the OVS
userspace daemon to setup the flows either in kernel or in HW using TC
flower offload.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>