floppy: cleanups: remove FLOPPY_SILENT_DCL_CLEAR undef

FLOPPY_SILENT_DCL_CLEAR is not defined anywhere and comes from pre-git
era. Just drop this undef. There is FD_SILENT_DCL_CLEAR which is really
used.
Signed-off-by: NDenis Efremov <efremov@linux.com>
Link: https://lore.kernel.org/r/20210416083449.72700-6-efremov@linux.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

drivers/block/floppy.c

@@ -145,8 +145,6 @@
  * Better audit of register_blkdev.
  */
 
-#undef  FLOPPY_SILENT_DCL_CLEAR
-
 #define REALLY_SLOW_IO
 
 #define DEBUGT 2