KVM: PPC: Book3s: PR: Add HV traps so we can run in HV=1 mode on p7

When running PR KVM on a p7 system in bare metal, we get HV exits instead
of normal supervisor traps. Semantically they are identical though and the
HSRR vs SRR difference is already taken care of in the exit code.

So all we need to do is handle them in addition to our normal exits.

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