s390_find_dev_by_idx() only indexes usable zpci devices. It implies
that the index value of each zpci device is dynamic and may change if
a new zpci device is plugged. So we have to use a constant index to
look up the device.
Signed-off-by: NYi Min Zhao <zyimin@linux.vnet.ibm.com>
Reviewed-by: NPierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>