net: usbnet: make driver_info const

The driver_info field that is used for describing each of the usb-net
drivers using the usbnet.c core all declare their information as const
and the usbnet.c itself does not try and modify the struct.

It is therefore a good idea to make this const in the usbnet.c structure
in case anyone tries to modify it.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index e2ec358..d8860f2 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -28,7 +28,7 @@
 	/* housekeeping */
 	struct usb_device	*udev;
 	struct usb_interface	*intf;
-	struct driver_info	*driver_info;
+	const struct driver_info *driver_info;
 	const char		*driver_name;
 	void			*driver_priv;
 	wait_queue_head_t	wait;