netdev-offload-tc: Re-fetch block ID after probing.

It's possible that block_id could changes after the probe for block
support.  Therefore, fetch the block_id again after the probe.

Fixes: edc2055 ("netdev-offload-tc: Flush rules on ingress block when init tc flow api")
Cc: Dmytro Linkin <dmitrolin@mellanox.com>
Acked-by: Roi Dayan <roid@mellanox.com>
Co-authored-by: Marcelo Leitner <mleitner@redhat.com>
Signed-off-by: Marcelo Leitner <mleitner@redhat.com>
Signed-off-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

lib/netdev-offload-tc.c

@@ -1931,6 +1931,8 @@ netdev_tc_init_flow_api(struct netdev *netdev)
 
     if (ovsthread_once_start(&block_once)) {
         probe_tc_block_support(ifindex);
+        /* Need to re-fetch block id as it depends on feature availability. */
+        block_id = get_block_id_from_netdev(netdev);
         ovsthread_once_done(&block_once);
     }