dm integrity: call kmem_cache_destroy() in dm_integrity_init() error path

commit 6b79a428 upstream.

Otherwise the journal_io_cache will leak if dm_register_target() fails.

Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>