f2fs: obsolete unused MAX_DISCARD_BLOCKS

After commit a7eeb823 ("f2fs: use bitmap in discard_entry"),
MAX_DISCARD_BLOCKS became obsolete, remove it.
Signed-off-by: Chao Yu <chao.yu@oppo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -230,7 +230,6 @@ enum {
 #define CP_PAUSE	0x00000040
 #define CP_RESIZE 	0x00000080
 
-#define MAX_DISCARD_BLOCKS(sbi)		BLKS_PER_SEC(sbi)
 #define DEF_MAX_DISCARD_REQUEST		8	/* issue 8 discards per round */
 #define DEF_MIN_DISCARD_ISSUE_TIME	50	/* 50 ms, if exists */
 #define DEF_MID_DISCARD_ISSUE_TIME	500	/* 500 ms, if device busy */