KVM: PPC: Book3S: PR: Handle EMUL_ASSIST

In addition to normal "priviledged instruction" traps, we can also receive
"emulation assist" traps on newer hardware that has the HV bit set.

Handle that one the same way as a privileged instruction, including the
instruction fetching. That way we don't execute old instructions that we
happen to still leave in that field when an emul assist trap comes.

This fixes -M mac99 / -M g3beige on p7 bare metal for me.

Signed-off-by: Alexander Graf <agraf@suse.de>