arcnet: com20020-pci: set dev_port to the subdevice index

This patch sets the dev_port according to the index of
the card. This can be used by udev to name the ports
in userspace.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
diff --git a/drivers/net/arcnet/com20020-pci.c b/drivers/net/arcnet/com20020-pci.c
index a12bf83..e3b7c14 100644
--- a/drivers/net/arcnet/com20020-pci.c
+++ b/drivers/net/arcnet/com20020-pci.c
@@ -96,6 +96,7 @@
 			ret = -ENOMEM;
 			goto out_port;
 		}
+		dev->dev_port = i;
 
 		dev->netdev_ops = &com20020_netdev_ops;