Comment 10 for bug 1561019

Ok so the patch which made this change can't be reverted bc there's been a lot of churn, but the effective equivalent of this would be to remove the svm line in:

static void pc_compat_2_1(MachineState *machine)
{
    pc_compat_2_2(machine);
    x86_cpu_change_kvm_default("svm", NULL);
}