Even if it is duplicated or we don't have an outbound message waiting, we should
ack it so that the firmware does not keep trying to send it to the host.
Otherwise the firmware could get into situations where it was constantly
retrying to send packets for which it did not receive our previous ACK and
exhaust memory.
I was only seeing this on platforms were packets were going missing in the
stream, increasing the probability that the driver would miss early responses.
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>
7168b87cb5