net: dsa: felix: start off with flooding disabled on the CPU port

The driver probes with all ports as standalone, and it supports unicast
filtering. So DSA will call port_fdb_add() for all necessary addresses
on the current CPU port. We also handle migrations when the CPU port
hardware resource changes (on tagging protocol change), so there should
not be any unknown address that we have to receive while not promiscuous.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>