KVM: VMX: Do not zero idt_vectoring_info in vmx_complete_interrupts().

We will need it later in task_switch().
Code in handle_exception() is dead. is_external_interrupt(vect_info)
will always be false since idt_vectoring_info is zeroed in
vmx_complete_interrupts().

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>