ext4: remove unused macro MB_DEFAULT_MAX_GROUPS_TO_SCAN

Signed-off-by: Robin Dong <sanbai@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/mballoc.h

@@ -64,11 +64,6 @@ extern u8 mb_enable_debug;
  */
 #define MB_DEFAULT_MIN_TO_SCAN		10
 
-/*
- * How many groups mballoc will scan looking for the best chunk
- */
-#define MB_DEFAULT_MAX_GROUPS_TO_SCAN	5
-
 /*
  * with 'ext4_mb_stats' allocator will collect stats that will be
  * shown at umount. The collecting costs though!