ssa.c: Close rsocket if ACM reconnects without disconnect

In case of port bouncing, ACM could reconnect to AL within
keepalive time interval. As result, AL could hold two connections
to the same ACM.

This patch removes the keepalive disabled check from
the code in ssa_check_listen_events which checked
for duplicated rsocket ID/number.

Original commit for that code segment:
commit d202bb6a685ef568f94ac37b02adbd3d3a8eb96f
Author: Sasha Kotchubievsky <sashakot@mellanox.com>
Date:   Thu Jul 31 14:40:33 2014 +0300

    ssa.c: Close old connection after fast client reconnection

    Only close connection if keepalive disabled (0).
    Otherwise, close stalls downstream thread (~33 seconds
    using default parameters).

    Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
    Signed-off-by: Hal Rosenstock <hal@mellanox.com>

Note that when duplicated connection is detected, underlying rclose
can stall downstream thread. Solution is to move the actual rclose
into a separate thread (and handle any errors appropriately in
rsocket calls in downstream thread if they could occur).

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>