x86-64, NUMA: Factor out memblk handling into numa_{add|register}_memblk()

Factor out memblk handling from srat_64.c into two functions in
numa_64.c.  This patch doesn't introduce any behavior change.  The
next patch will make all init methods use these functions.

- v2: Fixed build failure on 32bit due to misplaced NR_NODE_MEMBLKS.
      Reported by Ingo.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shaohui Zheng <shaohui.zheng@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/acpi.h

@@ -187,7 +187,6 @@ struct bootnode;
 extern int acpi_numa;
 extern int x86_acpi_numa_init(void);
 extern int acpi_scan_nodes(void);
-#define NR_NODE_MEMBLKS (MAX_NUMNODES*2)
 
 #ifdef CONFIG_NUMA_EMU
 extern void acpi_fake_nodes(const struct bootnode *fake_nodes,