nfs: testing the wrong variable

The intent was to test "*desc" for allocation failures, but it tests
"desc" which is always a valid pointer here.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/idmap.c

@@ -123,7 +123,7 @@ static ssize_t nfs_idmap_get_desc(const char *name, size_t namelen,
 	size_t desclen = typelen + namelen + 2;
 
 	*desc = kmalloc(desclen, GFP_KERNEL);
-	if (!desc)
+	if (!*desc)
 		return -ENOMEM;
 
 	cp = *desc;