mm/shmem: remove unneeded xa_is_value() check in shmem_unuse_swap_entries()

mm/shmem: remove unneeded xa_is_value() check in shmem_unuse_swap_entries()

As only value entry will be added to fbatch in shmem_find_swap_entries(),
there is no need to do xa_is_value() check in shmem_unuse_swap_entries().

Link: https://lkml.kernel.org/r/20250516170939.965736-6-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>