lib/stackdepot: fix comment in include/linux/stackdepot.h

As stack traces can now be evicted from the stack depot, remove the
comment saying that they are never removed.

Link: https://lkml.kernel.org/r/0ebe712d91f8d302a8947d3c9e9123bc2b1b8440.1703020707.git.andreyknvl@google.com
Fixes: 108be8de ("lib/stackdepot: allow users to evict stack traces")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/stackdepot.h

@@ -11,8 +11,6 @@
  * SLUB_DEBUG needs 256 bytes per object for that). Since allocation and free
  * stack traces often repeat, using stack depot allows to save about 100x space.
  *
- * Stack traces are never removed from the stack depot.
- *
  * Author: Alexander Potapenko <glider@google.com>
  * Copyright (C) 2016 Google, Inc.
  *