[IA64] numa.c, discontig.c: sparse: use NULL, not 0

Clean up a couple of places that were using 0 instead of NULL, which is the
more proper value.
Signed-off-by: Jesse Barnes <jbarnes@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/mm/discontig.c

@@ -681,7 +681,7 @@ void paging_init(void)
 				PAGE_ALIGN(max_low_pfn * sizeof(struct page));
 			vmem_map = (struct page *) vmalloc_end;
 
-			efi_memmap_walk(create_mem_map_page_table, 0);
+			efi_memmap_walk(create_mem_map_page_table, NULL);
 			printk("Virtual mem_map starts at 0x%p\n", vmem_map);
 		}
 

arch/ia64/mm/numa.c

@@ -70,7 +70,7 @@ static int __init topology_init(void)
 	memset(sysfs_cpus, 0, sizeof(struct cpu) * NR_CPUS);
 
 	for (i = 0; i < numnodes; i++)
-		if ((err = register_node(&sysfs_nodes[i], i, 0)))
+		if ((err = register_node(&sysfs_nodes[i], i, NULL)))
 			goto out;
 
 	for (i = 0; i < NR_CPUS; i++)