procfs: remove sparse errors in proc_devtree.c

CHECK fs/proc/proc_devtree.c
fs/proc/proc_devtree.c:197:14: warning: Using plain integer as NULL pointer
fs/proc/proc_devtree.c:203:34: warning: Using plain integer as NULL pointer
fs/proc/proc_devtree.c:210:14: warning: Using plain integer as NULL pointer
fs/proc/proc_devtree.c:223:26: warning: Using plain integer as NULL pointer
fs/proc/proc_devtree.c:226:14: warning: Using plain integer as NULL pointer

Signed-off-by: Michal Simek <[e-mail]>
Cc: Alexey Dobriyan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/proc/proc_devtree.c

···
 			p = fixup_name(np, de, p);
 
 		ent = proc_mkdir(p, de);
-		if (ent == 0)
+		if (ent == NULL)
 			break;
 		proc_device_tree_add_node(child, ent);
 	}
 	of_node_put(child);
 
-	for (pp = np->properties; pp != 0; pp = pp->next) {
+	for (pp = np->properties; pp != NULL; pp = pp->next) {
 		p = pp->name;
 
 		if (duplicate_name(de, p))
 			p = fixup_name(np, de, p);
 
 		ent = __proc_device_tree_add_prop(de, pp, p);
-		if (ent == 0)
+		if (ent == NULL)
 			break;
 	}
 }
···
 	struct device_node *root;
 
 	proc_device_tree = proc_mkdir("device-tree", NULL);
-	if (proc_device_tree == 0)
+	if (proc_device_tree == NULL)
 		return;
 	root = of_find_node_by_path("/");
-	if (root == 0) {
+	if (root == NULL) {
 		printk(KERN_ERR "/proc/device-tree: can't find root\n");
 		return;
 	}