net: dsa: b53: skip multicast entries for fdb_dump()

port_fdb_dump() is supposed to only add fdb entries, but we iterate over
the full ARL table, which also includes multicast entries.

So check if the entry is a multicast entry before passing it on to the
callback().

Additionally, the port of those entries is a bitmask, not a port number,
so any included entries would have even be for the wrong port.

Fixes: 1da6df85c6fb ("net: dsa: b53: Implement ARL add/del/dump operations")
Signed-off-by: Jonas Gorski <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/dsa/b53/b53_common.c

···
 	if (!ent->is_valid)
 		return 0;
 
+	if (is_multicast_ether_addr(ent->mac))
+		return 0;
+
 	if (port != ent->port)
 		return 0;