[PATCH] USB: minor gadget/rndis tweak

Resove a minor FIXME:  don't change MTU while RNDIS link is active,
the other end won't expect such things...
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/ether.c

@@ -1549,7 +1549,8 @@ static int eth_change_mtu (struct net_device *net, int new_mtu)
 {
 	struct eth_dev	*dev = netdev_priv(net);
 
-	// FIXME if rndis, don't change while link's live
+	if (dev->rndis)
+		return -EBUSY;
 
 	if (new_mtu <= ETH_HLEN || new_mtu > ETH_FRAME_LEN)
 		return -ERANGE;