KVM: x86: Update APICv on APIC reset

In kvm_apic_set_state() we update the hardware virtualized APIC after
the full APIC state has been overwritten. Do the same, when the full
APIC state has been reset in kvm_lapic_reset().

This updates some hardware state that was previously forgotten, as
far as I can tell. Also, this allows removing some APIC-related reset
code from vmx_vcpu_reset().

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>