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>
diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index c2c4163..65c7d91 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -310,7 +310,7 @@
 	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;