NFSv4: Simplify the struct nfs4_stateid

Replace the union with the common struct stateid4 as defined in both
RFC3530 and RFC5661. This makes it easier to access the sequence id,
which will again make implementing support for parallel OPEN calls
easier.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 55c8a81c..1dad5c5 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1240,8 +1240,8 @@
 				 * Open state on this file cannot be recovered
 				 * All we can do is revert to using the zero stateid.
 				 */
-				memset(state->stateid.data, 0,
-					sizeof(state->stateid.data));
+				memset(&state->stateid, 0,
+					sizeof(state->stateid));
 				/* Mark the file as being 'closed' */
 				state->state = 0;
 				break;