sparse pointer use of zero as null

Get rid of sparse related warnings from places that use integer as NULL
pointer.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ae2959b..034617f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1020,7 +1020,7 @@
 	 * size such that we can guarentee to record the reservation. */
 	if (&rg->link == head || t < rg->from) {
 		nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
-		if (nrg == 0)
+		if (!nrg)
 			return -ENOMEM;
 		nrg->from = f;
 		nrg->to   = f;