staging:rtl8192u: Add SPDX-License-Identifier - Style

Add SPDX-License-Identifier tag to the start of header file. This is
a coding style change which should have no impact on runtime code
execution.
Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/r8192U.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * This is part of rtl8187 OpenSource driver.
  * Copyright (C) Andrea Merello 2004-2005  <andrea.merello@gmail.com>