mm/page_cgroup.c: simplify code by using SECTION_ALIGN_UP() and SECTION_ALIGN_DOWN() macros

Commit a539f353 ("mm: add SECTION_ALIGN_UP() and
SECTION_ALIGN_DOWN() macro") introduced the SECTION_ALIGN_UP() and
SECTION_ALIGN_DOWN() macros.  Use those macros to increase code
readability.
Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_cgroup.c

@@ -225,8 +225,8 @@ int __meminit online_page_cgroup(unsigned long start_pfn,
 	unsigned long start, end, pfn;
 	int fail = 0;
 
-	start = start_pfn & ~(PAGES_PER_SECTION - 1);
-	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+	start = SECTION_ALIGN_DOWN(start_pfn);
+	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 
 	if (nid == -1) {
 		/*
@@ -258,8 +258,8 @@ int __meminit offline_page_cgroup(unsigned long start_pfn,
 {
 	unsigned long start, end, pfn;
 
-	start = start_pfn & ~(PAGES_PER_SECTION - 1);
-	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
+	start = SECTION_ALIGN_DOWN(start_pfn);
+	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 
 	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
 		__free_page_cgroup(pfn);