f2fs: correct comment in segment.h

s/two/three
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.h

@@ -142,7 +142,7 @@ enum {
 };
 
 /*
- * In the victim_sel_policy->alloc_mode, there are two block allocation modes.
+ * In the victim_sel_policy->alloc_mode, there are three block allocation modes.
  * LFS writes data sequentially with cleaning operations.
  * SSR (Slack Space Recycle) reuses obsolete space without cleaning operations.
  * AT_SSR (Age Threshold based Slack Space Recycle) merges fragments into
@@ -155,7 +155,7 @@ enum {
 };
 
 /*
- * In the victim_sel_policy->gc_mode, there are two gc, aka cleaning, modes.
+ * In the victim_sel_policy->gc_mode, there are three gc, aka cleaning, modes.
  * GC_CB is based on cost-benefit algorithm.
  * GC_GREEDY is based on greedy algorithm.
  * GC_AT is based on age-threshold algorithm.