mm/page_alloc: make boot_nodestats static

It's only used in mm/page_alloc.c now. Make it static.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Reviewed-by: David Hildenbrand <[e-mail]>
Reviewed-by: Anshuman Khandual <[e-mail]>
Reviewed-by: Oscar Salvador <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

mm/internal.h

···
  */
 struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags);
 
-DECLARE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
-
 extern bool mirrored_kernelcore;
 
 static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)

mm/page_alloc.c

···
 #define BOOT_PAGESET_BATCH	1
 static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
 static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
-DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
+static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
 
 static void __build_all_zonelists(void *data)
 {