vmw_balloon: update copyright message

Removing the GPL wording and replace it with an SPDX tag. The immediate
trigger for doing it now is the need to remove the list of maintainers
from the source file, as the maintainer list changed.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/vmw_balloon.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * VMware Balloon driver.
  *
- * Copyright (C) 2000-2014, VMware, Inc. All Rights Reserved.
+ * Copyright (C) 2000-2018, VMware, Inc. All Rights Reserved.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License as published by the
- * Free Software Foundation; version 2 of the License and no later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
- * NON INFRINGEMENT.  See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Maintained by:	Xavier Deguillard <xdeguillard@vmware.com>
- *			Philip Moltmann <moltmann@vmware.com>
- */
-
-/*
  * This is VMware physical memory management driver for Linux. The driver
  * acts like a "balloon" that can be inflated to reclaim physical pages by
  * reserving them in the guest and invalidating them in the monitor,