mm/khugepaged: use KMEM_CACHE()

mm/khugepaged: use KMEM_CACHE()

We got some late review commits during review of commit b4c9ffb54b32
("mm/khugepaged: remove definition of struct khugepaged_mm_slot").  No
need to keep the old cache name "khugepaged_mm_slot", let's simply use
KMEM_CACHE().

Link: https://lkml.kernel.org/r/20251001091900.20041-3-richard.weiyang@gmail.com
Fixes: b4c9ffb54b32 ("mm/khugepaged: remove definition of struct khugepaged_mm_slot")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Kiryl Shutsemau <kirill@shutemov.name>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: SeongJae Park <sj@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>