Drivers: hv: utils: Remove util transport handler from list if registration fails

BugLink: http://bugs.launchpad.net/bugs/1541585

If util transport fails to initialize for any reason, the list of transport
handlers may become corrupted due to freeing the transport handler without
removing it from the list. Fix this by cleaning it up from the list.
Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit e66853b0)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/hv/hv_utils_transport.c

@@ -310,6 +310,9 @@ struct hvutil_transport *hvutil_transport_init(const char *name,
 	return hvt;
 
 err_free_hvt:
+	spin_lock(&hvt_list_lock);
+	list_del(&hvt->list);
+	spin_unlock(&hvt_list_lock);
 	kfree(hvt);
 	return NULL;
 }