iavf: use tc_cls_can_offload_and_chain0() instead of chain check

Looks like the iavf code actually experienced a race condition, when a
developer took code before the check for chain 0 was put to helper.
So use tc_cls_can_offload_and_chain0() helper instead of direct check and
move the check to _cb() so this is similar to i40e code.

Signed-off-by: Jiri Pirko <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/intel/iavf/iavf_main.c

···
 static int iavf_setup_tc_cls_flower(struct iavf_adapter *adapter,
 				    struct flow_cls_offload *cls_flower)
 {
-	if (cls_flower->common.chain_index)
-		return -EOPNOTSUPP;
-
 	switch (cls_flower->command) {
 	case FLOW_CLS_REPLACE:
 		return iavf_configure_clsflower(adapter, cls_flower);
···
 static int iavf_setup_tc_block_cb(enum tc_setup_type type, void *type_data,
 				  void *cb_priv)
 {
+	struct iavf_adapter *adapter = cb_priv;
+
+	if (!tc_cls_can_offload_and_chain0(adapter->netdev, type_data))
+		return -EOPNOTSUPP;
+
 	switch (type) {
 	case TC_SETUP_CLSFLOWER:
 		return iavf_setup_tc_cls_flower(cb_priv, type_data);