s390/qeth: don't clear Output buffers on every queue init

On the first initialization of a queue, its Output Buffers are in a
clean state with no attached resources. On every subsequent
initialization, qeth_l?_stop_card() has previously put them in a clean
state via qeth_drain_output_queues(). So the call to
qeth_clear_output_buffer() is redundant and can be removed.

While at it, move the initialization of the queue's card pointer into
the queue allocation. It never changes afterwards.

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