[PATCH] remove unnecessary headers from mm_page_alloc.c

page_alloc.c does not use either slab.h or swapctl.h. This removes the
inclusion of those headers from page_alloc.c

mm/page_alloc.c

@@ -15,11 +15,9 @@
 #include <linux/config.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
-#include <linux/swapctl.h>
 #include <linux/interrupt.h>
 #include <linux/pagemap.h>
 #include <linux/bootmem.h>
-#include <linux/slab.h>
 #include <linux/compiler.h>
 #include <linux/module.h>
 #include <linux/suspend.h>