cxgb4i : Don't block unload/cxgb4 unload when remote closes TCP connection

cxgb4i was returning wrong error and not releasing module reference if remote
end abruptly closed TCP connection. This prevents the cxgb4 network module from
being unloaded, further affecting other network drivers dependent on cxgb4

Sending to net as this affects all cxgb4 based network drivers.

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>