Fixes for SRIOV in mlx5core.

- call pci_iov_detach() on detaching from PCI device to take care of hang
  on destroying VFs after PF is down.

- disable eswitch SRIOV support right after pci_iov_detach(),
  else the eswitch cleanup sometimes occur while the SRIOV flow table
  is still present.

Submitted by: kib@
MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking

sys/dev/mlx5/mlx5_core/mlx5_main.c

@@ -1664,6 +1664,11 @@ static void remove_one(struct pci_dev *pdev)
 	struct mlx5_core_dev *dev  = pci_get_drvdata(pdev);
 	struct mlx5_priv *priv = &dev->priv;
 
+#ifdef PCI_IOV
+	pci_iov_detach(pdev->dev.bsddev);
+	mlx5_eswitch_disable_sriov(priv->eswitch);
+#endif
+
 	if (mlx5_unload_one(dev, priv, true)) {
 		mlx5_core_err(dev, "mlx5_unload_one() failed, leaked %lld bytes\n",
 		    (long long)(dev->priv.fw_pages * MLX5_ADAPTER_PAGE_SIZE));