thunderbolt: Fix memory leak in margining_port_remove()

commit ac43c91 upstream.

The dentry returned by debugfs_lookup() needs to be released by calling
dput() which is missing in margining_port_remove(). Fix this by calling
debugfs_lookup_and_remove() that combines both and avoids the memory leak.

Fixes: d0f1e0c ("thunderbolt: Add support for receiver lane margining")
Cc: stable@vger.kernel.org
Signed-off-by: Yaxiong Tian <tianyaxiong@kylinos.cn>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Yaxiong Tian

drivers/thunderbolt/debugfs.c

@@ -959,7 +959,7 @@ static void margining_port_remove(struct tb_port *port)
 	snprintf(dir_name, sizeof(dir_name), "port%d", port->port);
 	parent = debugfs_lookup(dir_name, port->sw->debugfs_dir);
 	if (parent)
-		debugfs_remove_recursive(debugfs_lookup("margining", parent));
+		debugfs_lookup_and_remove("margining", parent);
 
 	kfree(port->usb4->margining);
 	port->usb4->margining = NULL;