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.