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

In commit 9c0ece069b ("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>

sound/Kconfig

@@ -52,9 +52,6 @@ config SOUND_OSS_CORE_PRECLAIM
 
 	  Disabling this allows alternative OSS implementations.
 
-	  Please read Documentation/feature-removal-schedule.txt for
-	  details.
-
 	  If unsure, say Y.
 
 source "sound/oss/dmasound/Kconfig"