net: dsa: b53: Do not program CPU port's PVID

[ Upstream commit 10163aae ]

The CPU port is special and does not need to obey VLAN restrictions as
far as untagged traffic goes, also, having the CPU port be part of a
particular PVID is against the idea of keeping it tagged in all VLANs.

Fixes: ca893194 ("net: dsa: b53: Keep CPU port as tagged in all VLANs")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/dsa/b53/b53_common.c

@@ -1175,7 +1175,7 @@ void b53_vlan_add(struct dsa_switch *ds, int port,
 		b53_fast_age_vlan(dev, vid);
 	}
 
-	if (pvid) {
+	if (pvid && !dsa_is_cpu_port(ds, port)) {
 		b53_write16(dev, B53_VLAN_PAGE, B53_VLAN_PORT_DEF_TAG(port),
 			    vlan->vid_end);
 		b53_fast_age_vlan(dev, vid);