mm: hugetlb_vmemmap: add check of CONFIG_MEMORY_HOTPLUG back

The compiler will optimize the code as much as possible if we add the
check of CONFIG_MEMORY_HOTPLUG back.

Link: https://lkml.kernel.org/r/20231205030530.3802-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb_vmemmap.c

@@ -119,7 +119,7 @@ static int vmemmap_pmd_entry(pmd_t *pmd, unsigned long addr,
 	 *   +--+ |                        |
 	 *        +------------------------+
 	 */
-	if (unlikely(!vmemmap_walk->nr_walked)) {
+	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && unlikely(!vmemmap_walk->nr_walked)) {
 		struct page *page = head ? head + pte_index(addr) :
 				    pte_page(ptep_get(pte_offset_kernel(pmd, addr)));