rds: tcp: canonical connection order for all paths with index > 0

The rds_connect_worker() has a bug in the check that enforces the
canonical connection order described in the comments of
rds_tcp_state_change(). The intention is to make sure that all
the multipath connections are always initiated by the smaller IP
address via rds_start_mprds. To achieve this, rds_connection_worker
should check that cp_index > 0.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>