KVM: vmx: disable APIC virtualization in nested guests

While running a nested guest, we should disable APIC virtualization
controls (virtualized APIC register accesses, virtual interrupt
delivery and posted interrupts), because we do not expose them to
the nested guest.

Reported-by: Hu Yaohui <loki2441@gmail.com>
Suggested-by: Abel Gordon <abel@stratoscale.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>