NFSv4: Deal with a sparse warning in nfs_idmap_get_key()

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Bryan Schumaker <bjschuma@netapp.com>

fs/nfs/idmap.c

@@ -310,7 +310,7 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
 	if (ret < 0)
 		goto out_up;
 
-	payload = rcu_dereference(rkey->payload.data);
+	payload = rcu_dereference(rkey->payload.rcudata);
 	if (IS_ERR_OR_NULL(payload)) {
 		ret = PTR_ERR(payload);
 		goto out_up;