dpaa2-eth: destroy workqueue at the end of remove function

The commit c5521189 ("dpaa2-eth: support PTP Sync packet one-step
timestamping") forgets to destroy workqueue at the end of remove
function.

Fix this by adding destroy_workqueue before fsl_mc_portal_free and
free_netdev.

Fixes: c5521189 ("dpaa2-eth: support PTP Sync packet one-step timestamping")
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -4550,6 +4550,8 @@ static int dpaa2_eth_remove(struct fsl_mc_device *ls_dev)
 
 	fsl_mc_portal_free(priv->mc_io);
 
+	destroy_workqueue(priv->dpaa2_ptp_wq);
+
 	dev_dbg(net_dev->dev.parent, "Removed interface %s\n", net_dev->name);
 
 	free_netdev(net_dev);