nfs: Do not try to use idmap for sec=mariux

Currently, operations which send uid or gid attributes (e.g. chgrp) try
to use idmap which results warnings like "Request-key: Cannot find
command to construct key 322998654" in the syslog, because we don't have
id_resolver configured in /etc/requesst-key.conf.

When the idmap operation fails, the uid of gid are send numerical, so
there is no problem aside from the log message.

Allow idmapping to be disabled for RPC_AITH_MARIUX just as for
RPC_AUTH_UNIX.

fs/nfs/nfs4client.c

@@ -1089,8 +1089,9 @@ static int nfs4_server_common_setup(struct nfs_server *server,
 	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
 	 * authentication.
 	 */
-	if (nfs4_disable_idmapping &&
-			server->client->cl_auth->au_flavor == RPC_AUTH_UNIX)
+	if (nfs4_disable_idmapping && (
+			server->client->cl_auth->au_flavor == RPC_AUTH_UNIX
+			|| server->client->cl_auth->au_flavor == RPC_AUTH_MARIUX ))
 		server->caps |= NFS_CAP_UIDGID_NOMAP;