kernel: fix integer as NULL pointer warnings

kernel/cpuset.c:1268:52: warning: Using plain integer as NULL pointer
kernel/pid_namespace.c:95:24: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Reviewed-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 024888b..48a976c 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1265,7 +1265,8 @@
 		return -E2BIG;
 
 	/* +1 for nul-terminator */
-	if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
+	buffer = kmalloc(nbytes + 1, GFP_KERNEL);
+	if (!buffer)
 		return -ENOMEM;
 
 	if (copy_from_user(buffer, userbuf, nbytes)) {