KVM: s390: protvirt: Handle SE notification interceptions

Since there is no interception for load control and load psw
instruction in the protected mode, we need a new way to get notified
whenever we can inject an IRQ right after the guest has just enabled
the possibility for receiving them.

The new interception codes solve that problem by providing a
notification for changes to IRQ enablement relevant bits in CRs 0, 6
and 14, as well a the machine check mask bit in the PSW.

No special handling is needed for these interception codes, the KVM
pre-run code will consult all necessary CRs and PSW bits and inject
IRQs the guest is enabled for.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Huth <thuth@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>