KVM: s390: protvirt: Support cmd 5 operation state

Code 5 for the set cpu state UV call tells the UV to load a PSW from
the SE header (first IPL) or from guest location 0x0 (diag 308 subcode
0/1). Also it sets the cpu into operating state afterwards, so we can
start it.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>