jbd2: fix incorrect unlock on j_list_lock

When 'jh->b_transaction == transaction' (asserted by below)

  J_ASSERT_JH(jh, (jh->b_transaction == transaction || ...

'journal->j_list_lock' will be incorrectly unlocked, since
the the lock is aquired only at the end of if / else-if
statements (missing the else case).

Signed-off-by: Taesoo Kim <tsgatesv@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Fixes: 6e4862a5
Cc: stable@vger.kernel.org # 3.14+