KVM: PPC: e500: Don't hardcode PIR=0

The hardcoded behavior prevents proper SMP support.

user space shall specify the vcpu's PIR as the vcpu id.

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