f2fs: fix typo

Fix typo and some grammatical errors.

The words "filesystem" and "readahead" are being used without the space treewide.

Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index d7947d9..87c50c5 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -58,7 +58,7 @@
 		 * 3. IO subsystem is idle by checking the # of requests in
 		 *    bdev's request list.
 		 *
-		 * Note) We have to avoid triggering GCs too much frequently.
+		 * Note) We have to avoid triggering GCs frequently.
 		 * Because it is possible that some segments can be
 		 * invalidated soon after by user update or deletion.
 		 * So, I'd like to wait some time to collect dirty segments.
@@ -222,7 +222,7 @@
 
 	u = (vblocks * 100) >> sbi->log_blocks_per_seg;
 
-	/* Handle if the system time is changed by user */
+	/* Handle if the system time has changed by the user */
 	if (mtime < sit_i->min_mtime)
 		sit_i->min_mtime = mtime;
 	if (mtime > sit_i->max_mtime)