jbd2: Use pr_notice_ratelimited() in journal_alloc_journal_head()

We had an open-coded version of printk_ratelimited(); use the provided
abstraction to make the code cleaner and easier to understand.

Based on a similar patch for fs/jbd from Namhyung Kim <namhyung@gmail.com>

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>