usbnet: printk format warning

Fix printk format warning(s):
drivers/usb/net/usbnet.c:654: warning: int format, different type arg (arg 3)

The fact that rx_urb_size happens to be a size_t has propagated all the way
back to this printk.  It's fragile to be using %z in this case - let's just
typecast the args instead.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/net/usbnet.c

@@ -653,7 +653,7 @@ static int usbnet_open (struct net_device *net)
 
 		devinfo (dev, "open: enable queueing "
 				"(rx %d, tx %d) mtu %d %s framing",
-			RX_QLEN (dev), TX_QLEN (dev), dev->net->mtu,
+			(int)RX_QLEN (dev), (int)TX_QLEN (dev), dev->net->mtu,
 			framing);
 	}