ctdb: Ensure ‘ret’ is always initialized

ctdb: Ensure ‘ret’ is always initialized

This avoids a compilation error:

../../ctdb/protocol/protocol_util.c: In function ‘ctdb_connection_list_read’:
../../ctdb/protocol/protocol_util.c:787:9: error: ‘ret’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  787 |  return ret;
      |         ^~~

Signed-off-by: Jo Sutton <josutton@catalyst.net.nz>
Reviewed-by: Martin Schwenke <martin@meltin.net>