net: stmmac: selftests: Guard VLAN Perfect test against non supported HW

When HW does not support perfect filtering the feature will not be
enabled in the net_device. Add a check for this to prevent failures.

Fixes: 1b2250a0 ("net: stmmac: selftests: Add tests for VLAN Perfect Filtering")
Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -971,6 +971,9 @@ static int stmmac_test_vlanfilt_perfect(struct stmmac_priv *priv)
 {
 	int ret, prev_cap = priv->dma_cap.vlhash;
 
+	if (!(priv->dev->features & NETIF_F_HW_VLAN_CTAG_FILTER))
+		return -EOPNOTSUPP;
+
 	priv->dma_cap.vlhash = 0;
 	ret = __stmmac_test_vlanfilt(priv);
 	priv->dma_cap.vlhash = prev_cap;
@@ -1063,6 +1066,9 @@ static int stmmac_test_dvlanfilt_perfect(struct stmmac_priv *priv)
 {
 	int ret, prev_cap = priv->dma_cap.vlhash;
 
+	if (!(priv->dev->features & NETIF_F_HW_VLAN_STAG_FILTER))
+		return -EOPNOTSUPP;
+
 	priv->dma_cap.vlhash = 0;
 	ret = __stmmac_test_dvlanfilt(priv);
 	priv->dma_cap.vlhash = prev_cap;