mm: use early_pfn_to_nid in register_page_bootmem_info_node

register_page_bootmem_info_node() is invoked in mem_init(), so it will
be called before page_alloc_init_late() if DEFERRED_STRUCT_PAGE_INIT is
enabled.  But, pfn_to_nid() depends on memmap which won't be fully setup
until page_alloc_init_late() is done, so replace pfn_to_nid() by
early_pfn_to_nid().

Link: http://lkml.kernel.org/r/1464210007-30930-1-git-send-email-yang.shi@linaro.org
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory_hotplug.c

@@ -300,7 +300,7 @@ void register_page_bootmem_info_node(struct pglist_data *pgdat)
 		 * multiple nodes we check that this pfn does not already
 		 * reside in some other nodes.
 		 */
-		if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
+		if (pfn_valid(pfn) && (early_pfn_to_nid(pfn) == node))
 			register_page_bootmem_info_section(pfn);
 	}
 }