net/mlx4_core: Use sink counter for the VF default as fallback

Some old PF drivers don't let VFs allocate counters, in that case, use
the sink counter so the VF can load and operate properly.

Fixes: 6de5f7f6a1fa ('net/mlx4_core: Allocate default counter per port')
Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/main.c

@@ -2273,6 +2273,11 @@ static int mlx4_allocate_default_counters(struct mlx4_dev *dev)
 		} else if (err == -ENOENT) {
 			err = 0;
 			continue;
+		} else if (mlx4_is_slave(dev) && err == -EINVAL) {
+			priv->def_counter[port] = MLX4_SINK_COUNTER_INDEX(dev);
+			mlx4_warn(dev, "can't allocate counter from old PF driver, using index %d\n",
+				  MLX4_SINK_COUNTER_INDEX(dev));
+			err = 0;
 		} else {
 			mlx4_err(dev, "%s: failed to allocate default counter port %d err %d\n",
 				 __func__, port + 1, err);