mm/compaction: avoid unneeded pageblock_end_pfn when no_set_skip_hint is set

Move pageblock_end_pfn after no_set_skip_hint check to avoid unneeded
pageblock_end_pfn if no_set_skip_hint is set.

Link: https://lkml.kernel.org/r/20230721150957.2058634-3-shikemeng@huawei.com
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>