0 -> NULL, for arch/x86_64

From: Yoann Padioleau <padator@wanadoo.fr>

When comparing a pointer, it's clearer to compare it to NULL than to 0.

Here is an excerpt of the semantic patch: 

@@
expression *E;
@@

  E ==
- 0
+ NULL

@@
expression *E;
@@

  E !=
- 0
+ NULL

Signed-off-by: Yoann Padioleau <padator@wanadoo.fr>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: ak@suse.de
Cc: discuss@x86-64.org
Cc: akpm@linux-foundation.org
---

 arch/x86_64/mm/numa.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/arch/x86_64/mm/numa.c
===================================================================
--- linux.orig/arch/x86_64/mm/numa.c
+++ linux/arch/x86_64/mm/numa.c
@@ -166,7 +166,7 @@ early_node_mem(int nodeid, unsigned long
 		return __va(mem);
 	ptr = __alloc_bootmem_nopanic(size,
 				SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS));
-	if (ptr == 0) {
+	if (ptr == NULL) {
 		printk(KERN_ERR "Cannot find %lu bytes in node %d\n",
 			size, nodeid);
 		return NULL;