include/linux/hugetlb.h: use bool instead of int for hugepage_migration_supported()

It is used as a pure bool function within kernel source wide.
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/hugetlb.h

@@ -452,12 +452,12 @@ static inline pgoff_t basepage_index(struct page *page)
 
 extern void dissolve_free_huge_pages(unsigned long start_pfn,
 				     unsigned long end_pfn);
-static inline int hugepage_migration_supported(struct hstate *h)
+static inline bool hugepage_migration_supported(struct hstate *h)
 {
 #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
 	return huge_page_shift(h) == PMD_SHIFT;
 #else
-	return 0;
+	return false;
 #endif
 }
 
@@ -519,7 +519,7 @@ static inline pgoff_t basepage_index(struct page *page)
 	return page->index;
 }
 #define dissolve_free_huge_pages(s, e)	do {} while (0)
-#define hugepage_migration_supported(h)	0
+#define hugepage_migration_supported(h)	false
 
 static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
 					   struct mm_struct *mm, pte_t *pte)