mm: make ref_unless functions unless_zero only

There are no users of (folio/page)_ref_add_unless(page, nr, u) with u != 0
[1] and all current users are "internal" for page refcounting API.  This
allows us to safely drop this parameter and reduce function semantics to
the "unless zero" cases only.

If needed, these functions for the u!=0 cases can be trivially
reintroduced later using the same atomic_add_unless operations as before.

[1]: The last user was dropped in v5.18 kernel, commit 27674ef6c73f ("mm:
remove the extra ZONE_DEVICE struct page refcount").  There is no trace of
discussion as to why this cleanup wasn't done earlier.

Link: https://lkml.kernel.org/r/a0c89b49d38c671a0bdd35069d15ee13e08314d2.1772370066.git.gladyshev.ilya1@h-partners.com
Co-developed-by: Gorbunov Ivan <gorbunov.ivan@h-partners.com>
Signed-off-by: Gorbunov Ivan <gorbunov.ivan@h-partners.com>
Signed-off-by: Gladyshev Ilya <gladyshev.ilya1@h-partners.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Kiryl Shutsemau <kas@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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