jbd2: don't leak memory if setting up journal fails

In journal_init_common(), if we failed to allocate the j_wbuf array, or
if we failed to create the buffer_head for the journal superblock, we
leaked the memory allocated for the revocation tables.  Fix this.

Cc: stable@vger.kernel.org # 4.9
Fixes: f0c9fd54
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>