dm clone: call kmem_cache_destroy() in dm_clone_init() error path

Otherwise the _hydration_cache will leak if dm_register_target() fails.

Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-clone-target.c

@@ -2205,6 +2205,7 @@ static int __init dm_clone_init(void)
 	r = dm_register_target(&clone_target);
 	if (r < 0) {
 		DMERR("Failed to register clone target");
+		kmem_cache_destroy(_hydration_cache);
 		return r;
 	}