sound: remove reference to feature-removal-schedule.txt

In commit 9c0ece069b32 ("Get rid of Documentation/feature-removal.txt"),
Linus removed feature-removal-schedule.txt from Documentation, but there
is still some reference to this file.  So remove them.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/sound/sound_core.c b/sound/sound_core.c
index fb9255c..bb23009 100644
--- a/sound/sound_core.c
+++ b/sound/sound_core.c
@@ -146,8 +146,7 @@
  * devices only the standard chrdev aliases are requested.
  *
  * All these clutters are scheduled to be removed along with
- * sound-slot/service-* module aliases.  Please take a look at
- * feature-removal-schedule.txt for details.
+ * sound-slot/service-* module aliases.
  */
 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
 static int preclaim_oss = 1;