mm: hugetlb_vmemmap: fix CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON

The following:

  commit 47010c0 ("mm: hugetlb_vmemmap: cleanup CONFIG_HUGETLB_PAGE_FREE_VMEMMAP*")

forgot to update CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON used in
vmemmap_optimize_mode to CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON. 
The result is we cannot enable hugetlb_optimize_vmemmap at boot time when
we configure CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON.  Fix it.

Link: https://lkml.kernel.org/r/20220527081948.68832-1-songmuchun@bytedance.com
Fixes: 47010c0 ("mm: hugetlb_vmemmap: cleanup CONFIG_HUGETLB_PAGE_FREE_VMEMMAP*")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb_vmemmap.c

@@ -33,7 +33,7 @@ DEFINE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON,
 EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key);
 
 static enum vmemmap_optimize_mode vmemmap_optimize_mode =
-	IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON);
+	IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON);
 
 static void vmemmap_optimize_mode_switch(enum vmemmap_optimize_mode to)
 {