s390x: do a subsystem reset before the unprotect on reboot

s390x: do a subsystem reset before the unprotect on reboot

Bound APQNs have to be reset before tearing down the secure config via
s390_machine_unprotect(). Otherwise the Ultravisor will return a error
code.

So let's do a subsystem_reset() which includes a AP reset before the
unprotect call. We'll do a full device_reset() afterwards which will
reset some devices twice. That's ok since we can't move the
device_reset() before the unprotect as it includes a CPU clear reset
which the Ultravisor does not expect at that point in time.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20230901114851.154357-1-frankja@linux.ibm.com>
Tested-by: Viktor Mihajlovski <mihajlov@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>