net: dsa: lantiq_gswip: treat VID 0 like the PVID

Documentation/networking/switchdev.rst says that VLAN-aware bridges must
treat packets tagged with VID 0 the same as untagged. It appears from
the documentation that setting the GSWIP_PCE_VCTRL_VID0 flag (which this
driver already had defined) might achieve this.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Link: https://patch.msgid.link/b220ac149922839a261b754202c05df5bb253c98.1760566491.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: vladimiroltean

drivers/net/dsa/lantiq/lantiq_gswip.c

@@ -603,15 +603,15 @@ static int gswip_port_vlan_filtering(struct dsa_switch *ds, int port,
 		gswip_switch_mask(priv,
 				  GSWIP_PCE_VCTRL_VSR,
 				  GSWIP_PCE_VCTRL_UVR | GSWIP_PCE_VCTRL_VIMR |
-				  GSWIP_PCE_VCTRL_VEMR,
+				  GSWIP_PCE_VCTRL_VEMR | GSWIP_PCE_VCTRL_VID0,
 				  GSWIP_PCE_VCTRL(port));
 		gswip_switch_mask(priv, GSWIP_PCE_PCTRL_0_TVM, 0,
 				  GSWIP_PCE_PCTRL_0p(port));
 	} else {
 		/* Use port based VLAN */
 		gswip_switch_mask(priv,
 				  GSWIP_PCE_VCTRL_UVR | GSWIP_PCE_VCTRL_VIMR |
-				  GSWIP_PCE_VCTRL_VEMR,
+				  GSWIP_PCE_VCTRL_VEMR | GSWIP_PCE_VCTRL_VID0,
 				  GSWIP_PCE_VCTRL_VSR,
 				  GSWIP_PCE_VCTRL(port));
 		gswip_switch_mask(priv, 0, GSWIP_PCE_PCTRL_0_TVM,