ctdb: Remove double sanity checks from ctdb_tcp_read_cb

ctdb: Remove double sanity checks from ctdb_tcp_read_cb

Within ctdb_tcp_read_cb the provided data is checked for sanity,
e.g. correct size and content. This is not required because it was
done already by the caller(queue_process).

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Martin Schwenke <martins@samba.org>
Autobuild-Date(master): Wed Apr  4 09:31:04 CEST 2018 on sn-devel-144