KVM: x86: fix lapic_timer_int_injected with APIC-v

With APICv, LAPIC timer interrupt is always delivered via IRR:
apic_find_highest_irr syncs PIR to IRR.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>