rndis_host: Fix sparse warning

rndis_unbind and usbnet_cdc_unbind don't return anything.

Signed-off-by: Bjorge Dijkstra <bjd@jooz.net>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/rndis_host.c

@@ -585,7 +585,7 @@ static void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
 		kfree(halt);
 	}
 
-	return usbnet_cdc_unbind(dev, intf);
+	usbnet_cdc_unbind(dev, intf);
 }
 
 /*