init: fix integer as NULL pointer warnings

init/do_mounts_rd.c:215:13: warning: Using plain integer as NULL pointer
init/do_mounts_md.c:136:45: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c
index 753dc54..7473b0c 100644
--- a/init/do_mounts_md.c
+++ b/init/do_mounts_md.c
@@ -133,7 +133,7 @@
 		else
 			dev = MKDEV(MD_MAJOR, minor);
 		create_dev(name, dev);
-		for (i = 0; i < MD_SB_DISKS && devname != 0; i++) {
+		for (i = 0; i < MD_SB_DISKS && devname != NULL; i++) {
 			char *p;
 			char comp_name[64];
 			u32 rdev;