KVM: s390: protvirt: Instruction emulation

We have two new SIE exit codes dealing with instructions.
104 (0x68) for a secure instruction interception, on which the SIE needs
hypervisor action to complete the instruction. We can piggy-back on the
existing instruction handlers.

108 which is merely a notification and provides data for tracking and
management. For example this is used to tell the host about a new value
for the prefix register. As there will be several special case handlers
in later patches, we handle this in a separate function.

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