uuid: discourage people from using UAPI header in new code

Discourage people from using UAPI header in new code by adding a note.

Link: https://lkml.kernel.org/r/20211216113552.81199-1-andriy.shevchenko@linux.intel.comSigned-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/uapi/linux/uuid.h

 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* DO NOT USE in new code! This is solely for MEI due to legacy reasons */
 /*
  * UUID/GUID definition
  *