net: stmmac: enable HW-accelerated VLAN stripping for gmac4 only

Commit 750011e ("net: stmmac: Add support for HW-accelerated VLAN
stripping") enables MAC level VLAN tag stripping for all MAC cores, but
leaves set_hw_vlan_mode() and rx_hw_vlan() un-implemented for both gmac
and xgmac.

On gmac and xgmac, ethtool reports rx-vlan-offload is on, both MAC and
driver do nothing about VLAN packets actually, although VLAN works well.

Driver level stripping should be used on gmac and xgmac for now.

Fixes: 750011e ("net: stmmac: Add support for HW-accelerated VLAN stripping")
Signed-off-by: Furong Xu <0x1207@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Furong Xu

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -7662,9 +7662,10 @@ int stmmac_dvr_probe(struct device *device,
 #ifdef STMMAC_VLAN_TAG_USED
 	/* Both mac100 and gmac support receive VLAN tag detection */
 	ndev->features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX;
-	ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX;
-	priv->hw->hw_vlan_en = true;
-
+	if (priv->plat->has_gmac4) {
+		ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX;
+		priv->hw->hw_vlan_en = true;
+	}
 	if (priv->dma_cap.vlhash) {
 		ndev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
 		ndev->features |= NETIF_F_HW_VLAN_STAG_FILTER;