KVM: PPC: Use now shadowed vcpu fields

The shadow vcpu now contains some fields we don't use from the vcpu anymore.
Access to them happens using inline functions that happily use the shadow
vcpu fields.

So let's now ifdef them out to booke only and add asm-offsets.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>