s390/qeth: cancel cmd on early error

When sending cmds via qeth_send_control_data(), qeth puts the request
on the IO channel and then blocks on the reply object until the response
has been received.

If the IO completes with error, there will never be a response and we
block until the reply-wait hits its timeout. For this case, connect the
request buffer to its reply object, so that we can immediately cancel
the wait.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>