net: stmmac: tc: Do not setup flower filtering if RSS is enabled

RSS, when enabled, will bypass the L3 and L4 filtering causing it not
to work. Add a check before trying to setup the filters.

Fixes: 425eabddaf ("net: stmmac: Implement L3/L4 Filters using TC Flower")
Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -577,6 +577,10 @@ static int tc_setup_cls(struct stmmac_priv *priv,
 {
 	int ret = 0;
 
+	/* When RSS is enabled, the filtering will be bypassed */
+	if (priv->rss.enable)
+		return -EBUSY;
+
 	switch (cls->command) {
 	case FLOW_CLS_REPLACE:
 		ret = tc_add_flow(priv, cls);