mm: Move definition of MIN_MEMORY_BLOCK_SIZE to a header

The macro MIN_MEMORY_BLOCK_SIZE is currently defined twice in two .c
files, and I need it in a third one to fix a powerpc bug, so let's
first move it into a header
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/init_64.c

@@ -28,6 +28,7 @@
 #include <linux/poison.h>
 #include <linux/dma-mapping.h>
 #include <linux/module.h>
+#include <linux/memory.h>
 #include <linux/memory_hotplug.h>
 #include <linux/nmi.h>
 #include <linux/gfp.h>
@@ -895,8 +896,6 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 }
 
 #ifdef CONFIG_X86_UV
-#define MIN_MEMORY_BLOCK_SIZE   (1 << SECTION_SIZE_BITS)
-
 unsigned long memory_block_size_bytes(void)
 {
 	if (is_uv_system()) {

drivers/base/memory.c

@@ -30,7 +30,6 @@
 static DEFINE_MUTEX(mem_sysfs_mutex);
 
 #define MEMORY_CLASS_NAME	"memory"
-#define MIN_MEMORY_BLOCK_SIZE	(1 << SECTION_SIZE_BITS)
 
 static int sections_per_block;
 

include/linux/memory.h

@@ -20,6 +20,8 @@
 #include <linux/compiler.h>
 #include <linux/mutex.h>
 
+#define MIN_MEMORY_BLOCK_SIZE     (1 << SECTION_SIZE_BITS)
+
 struct memory_block {
 	unsigned long start_section_nr;
 	unsigned long end_section_nr;