s390/drivers: use setup_timer

Use setup_timer function instead of initializing timer with the
function and data fields.

Signed-off-by: Allen Pais <allen.lkml@gmail.com>
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>