mm: madvise: use vm_normal_folio() in madvise_free_pte_range()

There is already a vm_normal_folio(), use it to make
madvise_free_pte_range() only use a folio.

Link: https://lkml.kernel.org/r/20230112124028.16964-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/madvise.c

@@ -617,7 +617,6 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 	spinlock_t *ptl;
 	pte_t *orig_pte, *pte, ptent;
 	struct folio *folio;
-	struct page *page;
 	int nr_swap = 0;
 	unsigned long next;
 
@@ -658,10 +657,9 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 			continue;
 		}
 
-		page = vm_normal_page(vma, addr, ptent);
-		if (!page || is_zone_device_page(page))
+		folio = vm_normal_folio(vma, addr, ptent);
+		if (!folio || folio_is_zone_device(folio))
 			continue;
-		folio = page_folio(page);
 
 		/*
 		 * If pmd isn't transhuge but the folio is large and