Currently ztailpacking pclusters are chained with FOLLOWED_NOINPLACE and
not recorded into the managed_pslots XArray.

After commit 7674a42f ("erofs: use struct lockref to replace
handcrafted approach"), ztailpacking pclusters won't be freed with
erofs_workgroup_put() anymore, which will cause the following issue:

BUG erofs_pcluster-1 (Tainted: G           OE     ): Objects remaining in erofs_pcluster-1 on __kmem_cache_shutdown()

Use z_erofs_free_pcluster() directly to free ztailpacking pclusters.

Fixes: 7674a42f ("erofs: use struct lockref to replace handcrafted approach")
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230822110530.96831-1-jefflexu@linux.alibaba.comSigned-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>