usbnet: Set link down initially for drivers that update link state

Some usbnet drivers update link state while others do not due to
hardware limitations.  Add a flag to distinguish those that do, and
set the link down initially for their devices.

This is intended to fix this bug: http://bugs.debian.org/444043

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 378da8c..04f3f28 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1352,9 +1352,11 @@
 	// ok, it's ready to go.
 	usb_set_intfdata (udev, dev);
 
-	// start as if the link is up
 	netif_device_attach (net);
 
+	if (dev->driver_info->flags & FLAG_LINK_INTR)
+		netif_carrier_off(net);
+
 	return 0;
 
 out3: