ipmi: Add or fix SPDX-License-Identifier in all files

And get rid of the license text that is no longer necessary.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alistair Popple <alistair@popple.id.au>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Rocky Craig <rocky.craig@hp.com>

drivers/char/ipmi/bt-bmc.c

@@ -1,10 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (c) 2015-2016, IBM Corporation.
- *
- * 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; either version
- * 2 of the License, or (at your option) any later version.
  */
 
 #include <linux/atomic.h>