bcache: remove unused constants

Remove constants MAX_NEED_GC and MAX_SAVE_PRIO in btree.c that have been unused
since initial commit.

Signed-off-by: Robert Pang <robertpang@google.com>
Signed-off-by: Coly Li <colyli@kernel.org>
Link: https://lore.kernel.org/r/20250527051601.74407-3-colyli@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: robert-pang

drivers/md/bcache/btree.c

@@ -88,8 +88,6 @@
  * Test module load/unload
  */
 
-#define MAX_NEED_GC		64
-#define MAX_SAVE_PRIO		72
 #define MAX_GC_TIMES		100
 #define MIN_GC_NODES		100
 #define GC_SLEEP_MS		100