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_rd.c b/init/do_mounts_rd.c
index 3ac5904..46dfd64 100644
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -212,7 +212,7 @@
 	}
 
 	buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
-	if (buf == 0) {
+	if (!buf) {
 		printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
 		goto done;
 	}