jbd2: Remove obsolete parameters in the comments for some jbd2 functions

credits isn't a parameter for jbd2_journal_get_write_access and
jbd2_journal_get_undo_access. So remove the corresponding comments.

Acked-by: Jan Kara <jack@suse.cz>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/jbd2/transaction.c

@@ -814,7 +814,6 @@ out:
  * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
  * @handle: transaction to add buffer modifications to
  * @bh:     bh to be used for metadata writes
- * @credits: variable that will receive credits for the buffer
  *
  * Returns an error code or 0 on success.
  *
@@ -932,7 +931,6 @@ out:
  *     non-rewindable consequences
  * @handle: transaction
  * @bh: buffer to undo
- * @credits: store the number of taken credits here (if not NULL)
  *
  * Sometimes there is a need to distinguish between metadata which has
  * been committed to disk and that which has not.  The ext3fs code uses