s390/qeth: fine-tune spinlocks

For quite a lot of code paths it's obvious that they will never run in
IRQ context. So replace their spin_lock_irqsave() calls with
spin_lock_irq().

While at it, get rid of the redundant card pointer in struct qeth_reply
that was used by qeth_send_control_data() to access the card's lock.

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