kvm: Fix eflags corruption in kvm mode

This should explain a lot of the weird breakages of upstream KVM we've
seen recently (actually we should have seen it much earlier):

Stop translating eflags into TCG format when in kvm mode as we never
translate it back and rather sync this broken state into the kernel.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
