mm: shmem: refactor thpsize_shmem_enabled_show() with helper arrays

mm: shmem: refactor thpsize_shmem_enabled_show() with helper arrays

Replace the hardcoded if/else chain of test_bit() calls and string
literals in thpsize_shmem_enabled_show() with a loop over
huge_shmem_orders_by_mode[] and huge_shmem_enabled_mode_strings[] arrays.

This makes thpsize_shmem_enabled_show() consistent with
thpsize_shmem_enabled_store() and eliminates duplicated mode name strings.

Link: https://lore.kernel.org/20260525102700.68707-3-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand (arm) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>