nilfs2: fix various typos in comments

This fixes various typos I found in comments of nilfs2.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 3265bfc..69576a9 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -201,7 +201,7 @@
  * This function allocates a nilfs_transaction_info struct to keep context
  * information on it.  It is initialized and hooked onto the current task in
  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
- * instead; othewise a new struct is assigned from a slab.
+ * instead; otherwise a new struct is assigned from a slab.
  *
  * When @vacancy_check flag is set, this function will check the amount of
  * free space, and will wait for the GC to reclaim disk space if low capacity.
@@ -2854,7 +2854,7 @@
  * @sbi: nilfs_sb_info
  *
  * nilfs_attach_segment_constructor() allocates a struct nilfs_sc_info,
- * initilizes it, and starts the segment constructor.
+ * initializes it, and starts the segment constructor.
  *
  * Return Value: On success, 0 is returned. On error, one of the following
  * negative error code is returned.