s390/hvc_iucv: Remove power management support

Power management support was removed for s390 with
commit 39421627 ("s390: remove broken hibernate / power management
support").

Remove the hvc_iucv_driver, but keep the device struct around so that
it can continue to provide the hvc_iucv_dev_attr_groups attributes.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>