net: dsa: Keep the vlan_filtering setting in dsa_switch if it's global

The current behavior is not as obvious as one would assume (which is
that, if the driver set vlan_filtering_is_global = 1, then checking any
dp->vlan_filtering would yield the same result). Only the ports which
are actively enslaved into a bridge would have vlan_filtering set.

This makes it tricky for drivers to check what the global state is.
So fix this and make the struct dsa_switch hold this global setting.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 9a6ed13..c27c16b 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -208,7 +208,10 @@ int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 	if (err)
 		return err;
 
-	dp->vlan_filtering = vlan_filtering;
+	if (ds->vlan_filtering_is_global)
+		ds->vlan_filtering = vlan_filtering;
+	else
+		dp->vlan_filtering = vlan_filtering;
 	return 0;
 }