staging: ozwpan: implement error handling in ozwpan_init()

Errors are correctly handled in oz_cdev_register() and oz_protocol_init(),
but then they are ignored in ozwpan_init().

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/ozwpan/ozmain.c

@@ -34,11 +34,21 @@ MODULE_PARM_DESC(g_net_dev, "The device(s) to bind to; "
  */
 static int __init ozwpan_init(void)
 {
-	oz_cdev_register();
-	oz_protocol_init(g_net_dev);
+	int err;
+
+	err = oz_cdev_register();
+	if (err)
+		return err;
+	err = oz_protocol_init(g_net_dev);
+	if (err)
+		goto err_protocol;
 	oz_app_enable(OZ_APPID_USB, 1);
 	oz_apps_init();
 	return 0;
+
+err_protocol:
+	oz_cdev_deregister();
+	return err;
 }
 
 /*