nfsd4: split stateowners into open and lockowners

The stateowner has some fields that only make sense for openowners, and
some that only make sense for lockowners, and I find it a lot clearer if
those are separated out.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index c4dcba3..182570be 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -646,7 +646,7 @@
 
 	memset(open->op_bmval, 0, sizeof(open->op_bmval));
 	open->op_iattr.ia_valid = 0;
-	open->op_stateowner = NULL;
+	open->op_openowner = NULL;
 
 	/* seqid, share_access, share_deny, clientid, ownerlen */
 	READ_BUF(16 + sizeof(clientid_t));