dpaa2-mac: fix the remove path for non-MAC interfaces

Check if the interface is indeed connected to a MAC before trying to
close the DPMAC object representing it. Without this check we end up
working with a NULL pointer.

Fixes: d87e606373 ("dpaa2-mac: export MAC counters even when in TYPE_FIXED")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Link: https://lore.kernel.org/r/20210111171802.1826324-1-ciorneiioana@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -4150,6 +4150,9 @@ static void dpaa2_eth_disconnect_mac(struct dpaa2_eth_priv *priv)
 	if (dpaa2_eth_is_type_phy(priv))
 		dpaa2_mac_disconnect(priv->mac);
 
+	if (!dpaa2_eth_has_mac(priv))
+		return;
+
 	dpaa2_mac_close(priv->mac);
 	kfree(priv->mac);
 	priv->mac = NULL;